Atomic Number Definition

[1] :20 Mass numbers are always whole numbers with no units. Every nuclide has a chemical element symbol (E) as well as an atomic number (Z) , the number of protons in the nucleus, and a mass number (A), the total number of protons and neutrons in the nucleus. It took roughly another decade before a new more complete atomic theory was developed - the modern atomic theory. Hybrid Orbitals. Return to top of page. So one other concept that might come up when you're thinking about atomic and ionic radii, might be this definition of an isoelectronic series and so that's when a group of ions containing the same number of electrons are being compared. Angular Momentum (Secondary, Azimunthal) Quantum Number 3. In an uncharged atom, the atomic number is also equal to the number of electrons. water as the moderator) can be simply changed leading into. - Remember that the mass number (a. In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus. The atomic number is the number of protons in a nucleus and it characterises a chemical element. The number of protons is called the " atomic number " and determines which element the atom is a particle of (and therefore also its chemical properties). Hydrogen, for example, has one proton and one electron; the element sulfur has 16 protons and 16 electrons. Scientific American is the essential guide to the most awe-inspiring advances in science and technology, explaining how they change our understanding of the world and shape our lives. Chemists would later organise each element by atomic number, not atomic weight, giving rise to the modern Periodic Table of Elements. Dictionary Definition of atomic number 53 a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks). Sodium is a chemical element, symbol Na and atomic number 11. Anyway, as you said, this is an average of the masses of the isotopes, weighted by their relative abundance. Find and lookup the definition, synonyms, and antonyms of the word atomic number 108 in our free online dictionary! Crossword Solver, Scrabble Word Finder, Scrabble Cheat Site Search. Example sentences containing atomic number 22. What does atomic number mean? Information and translations of atomic number in the most comprehensive dictionary definitions resource on the web. Students will answer true/false questions and complete a table with elements, atomic numbers, and number of electrons. The atomic number is the number of protons in an atom, and isotopes have the same atomic number but differ in the number of neutrons. For the first time it became possible to predict exactly how many elements remained to be discovered. Find and lookup the definition, synonyms, and antonyms of the word atomic number 19 in our free online dictionary! Crossword Solver, Scrabble Word Finder, Scrabble Cheat Site Search. for example: the atomic number for hydogen is 1. For example, if an atom has a Z of 6, it is carbon , while a Z of 92 corresponds to uranium. Standard Atomic Weight The standard atomic weight is the average mass of an element in atomic mass units ("amu"). In other words, 1 amu = 1 gram/mole. Answer Four: By the Generalized Definition of Prime. atomic structure n the concept of an atom as a central positively charged nucleus consisting of protons and neutrons surrounded by a number of electrons. Copyright © 2017 chemicool. Part of: brine, saltwater, seawater. What does atomic number 10 mean as a name of something? noun. The periodic table represents neutral atoms. Magnetic Quantum Number (m l) 4. The research was. Atomic Weight: The average mass of an atom of an element, usually expressed in atomic mass units. The atomic number uniquely identifies a chemical element. The atomic numbers go in order on the table. In addition to protons, the atoms of nearly every element also contain neutrons. Angular Momentum (Secondary, Azimunthal) Quantum Number 3. Atomic number definition: the number of protons in the nucleus of an atom of an element | Meaning, pronunciation, translations and examples. com! The Web's largest and most authoritative phrases and idioms resource. The atomic number of an element is the same as the number of electrons or protons in that particular atom. Z (Atomic number) synonyms, Z (Atomic number) pronunciation, Z (Atomic number) translation, English dictionary definition of Z (Atomic number). There are two trends taking place when you look at the elements in the periodic table. So if you have just 1 mole, the number of grams will be the atomic mass. In an atom of neutral charge, the atomic number is also equal to the number of electrons. Atomic number and mass number are always whole numbers because they are obtained by counting whole objects (protons, neutrons, and electrons). net dictionary. Atomic number is always determined by the number of protons. This has many features, and comes in both a Windows version and a command-line interface version. Every element has separate atomic number, and no element has the same atomic number. The variation in the number of protons in the nucleus of an atom, for example during a nuclear reaction, changes the element in question. Assets can be defined as hardware, data, or people. For example, Hydrogen has the atomic number of 1 and Oxygen has the atomic number of 8. atomic number 42 synonyms, atomic number 42 pronunciation, atomic number 42 translation, English dictionary definition of atomic number 42. Interesting facts: It is created as a result of radioactive decay. net dictionary. atomic number. Start studying Atomic Number and Mass Number. Transactions are made private by a privacy enhancement in the protocol called "minting". 205 atom percent natural abundance. Elements are defined by the number of protons in the atomic nucleus. Students will answer true/false questions and complete a table with elements, atomic numbers, and number of electrons. The definition is OK of course but you rarely use it. Looking for definition of atomic number 60? atomic number 60 explanation. In other words, 1 amu = 1 gram/mole. Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid. The higher the atomic number, the more shells and electrons an atom will have. Gold has 79 protons in each atom and has an atomic number of 79. What Is an Atomic Number? Develop students' understanding of physical science concepts with this printable on atomic numbers. Start studying Atomic Number and Mass Number. the number indicating the order of a chemical element in the periodic system of elements of D. Since many elements have a number of isotopes, and since chemists rarely work with one atom at a time, chemists use average atomic mass. The 2p and 3p Orbitals. Around the nucleus are a equal number of negatively charged electrons. This relationship means that if we had Avogadro's number, or one mole, of carbon-12 atoms (which has an atomic weight of 12 amu by definition), that sample of carbon-12 would weigh exactly 12 grams. The number of electrons in a neutral atom is equal to the number of protons. Atomic Number. Atomic radius is generally stated as being the total distance from an atom's nucleus to the outermost orbital of electron. In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus. Related words - atomic number 22 synonyms, antonyms, hypernyms and hyponyms. The number associated with an isotope is its atomic mass (i. MnemonicDictionary. What are synonyms for atomic number?. atomic structure n the concept of an atom as a central positively charged nucleus consisting of protons and neutrons surrounded by a number of electrons. For a given atomic number the number of neutrons defines the different isotopes of this element. the number indicating the order of a chemical element in the periodic system of elements of D. For example, if an atom has a Z of 6, it is carbon , while a Z of 92 corresponds to uranium. net dictionary. The atomic number is the number of protons — positively charged particles — in the nucleus an atom of a chemical element. Every element has separate atomic number, and no element has the same atomic number. The modern periodic table is ordered by increasing atomic number. So if an element has an atomic number of 5, you know that it has 5 protons and 5 electrons. Though individual atoms always have an integer number of atomic mass units, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element. Atomic Weight: Atomic weight of an atom is the average mass of an atom of a particular element that is calculated using the relative abundance of isotopes. So if you have just 1 mole, the number of grams will be the atomic mass. In a neutral atom, the atomic number is equal to the number of electrons orbiting the nucleus. What does atomic number mean in law?. For a given atomic number the number of neutrons defines the different isotopes of this element. org Dictionary. Meaning of atomic number 73. The effect of the spin-spin interaction is noted in Hund's rule #1. The atomic number is simply the number of protons in an atom. For example, an atom with 6 protons must be carbon, and an atom with 92 protons must be uranium. The atomic number determines which element an atom is. We tend not to notice them. Find descriptive alternatives for atomic number. Supplier Information Download. All atoms of an element have the same number of electrons (i. Synonyms for atomic number at Thesaurus. It is similar to the charge number of the nucleus and is represented by symbol Z. Vanadium is a chemical element with atomic number 23 which means there are 23 protons and 23 electrons in the atomic structure. Number of neutrons = A - Z Isotopes Isotopes are atoms with the same number of protons, but different numbers of neutrons. You take the number of moles and multiply it by the atomic mass. If an atom has one proton then the atomic number is 1 and the element is hydrogen. Number of neutrons = A - Z Isotopes Isotopes are atoms of same element with the same number of protons, but different numbers of neutrons. the order of an element in Mendeleyev's table of the elements; equal to the number of protons in the nucleus or electrons in the neutral state of an atom of an element Scrapingweb Dictionary DB. Avogadro's number ( N ) ( N A ) the number of molecules in one mole of a substance: 6. Because the protons are. Louis de Brogllie introduces the wave/particle duality of matter (1921) Traditional (classical) physics had assumed that particles were particles and waves were waves and thats that. Every cesium atom has 55 protons and hence the atomic number is 55. Atomic Number: Atomic number is the total number of protons present in the nucleus of an atom. This both numbers are different by the definition itself. ’ ‘We now have data on the properties of 29 new nuclei with atomic numbers between 104 and 118. Atomic Weight: Atomic weight of an atom is the average mass of an atom of a particular element that is calculated using the relative abundance of isotopes. The atomic number of an element is equal to the total number of protons in the element's nucleus and is commonly represented as the letter Z. This has many features, and comes in both a Windows version and a command-line interface version. The atomic number, Z, is the number of protons in the nucleus. The atomic mass is in the order of the average number of protons and neutrons permitting the relative abundance of different isotopes. Around the nucleus are a equal number of negatively charged electrons. Find out more about Atomic Number 104 on Wikipedia. It is nonflammable. Astatine: Atomic mass number given for longest lived isotope. Angular Momentum (Secondary, Azimunthal) Quantum Number 3. The page not only provides Urdu meaning of Atomic Number but also gives extensive definition in English language. The theoretical values of the Z eff are also calculated using the formula given by Jackson and Hawkes[ 2 ] and these values are discussed in the light of the dosimetry point. Find descriptive alternatives for atomic number. This is the average atomic mass of carbon. Define and determine the mass number of an atom. Number of protons in an atom. , the region in space) in which an. Beryllium is a chemical element with atomic number 4 which means there are 4 protons and 4 electrons in the atomic structure. Atomic mass of Beryllium is 9. The total number of protons and neutrons in a nucleus is called the atom's mass number. Sodium is a chemical element, symbol Na and atomic number 11. Atomic Orbitals. Notes on the Atomic Mass of particular elements: Technetium: Atomic mass number given for longest lived isotope. Start studying Atomic Number and Mass Number. The total number of protons and neutrons in the nucleus of the atom is called the " mass number " and is determined by the type of atom (i. Its the most abundant element known in the universe after hydrogen. In today’s report, I will be assessing the fundamental and technical strengths and weaknesses of Constellation. Atomic Number is the number of protons present in the nucleus of an element. The atomic number is represented by the symbol Z, and represents the number of protons in an atom. It helps to predict how one element will react with another. A mole of any atoms has a mass in grams equal to the atomic weight of the element. 022 × 10 23 particles The mass of 1 mole of carbon-12 atoms is 12 g The atomic weight of an element is defined as its mass relative to carbon-12. The chemical symbol for Beryllium is Be. There are various models for atomic structure DEFINITION: Relative isotopic mass is. The Scientific Monthly by American Association for the Advancement of Science (1922). 022 × 10 23 particles The mass of 1 mole of carbon-12 atoms is 12 g The atomic weight of an element is defined as its mass relative to carbon-12. Sir William Ramsay discovered helium on earth (1895) Common Compounds: No stable compounds are formed with helium. Another way of naming isotopes uses the name of the element followed by the isotope’s mass number. What does atomic number mean? Information and translations of atomic number in the most comprehensive dictionary definitions resource on the web. The atomic number (symbol: Z) of an atom is the number of protons in the nucleus of the atom. atomic number. Number of neutrons = A - Z Isotopes Isotopes are atoms of same element with the same number of protons, but different numbers of neutrons. Except for hydrogen, the nucleus also has neutrons. The atomic number determines the identity of an element and many of its chemical properties. What does atomic number mean? Proper usage and audio pronunciation (plus IPA phonetic transcription) of the word atomic number. Definition of Atomic Mass. All atoms of a particular element will have the same atomic number, however they may differ in their number of neutrons and electrons. Atomic number and mass number are always whole numbers because they are obtained by counting whole objects (protons, neutrons, and electrons). A LEVEL CHEMISTRY - SOME DEFINITIONS TO LEARN ISOTOPE Atoms with the same atomic number but different mass number or the same number of protons but different numbers of neutrons ATOMIC NUMBER The number of protons in the nucleus of an atom MASS NUMBER The sum of the protons and neutrons in the nucleus of an atom. NCERT Solutions In text and Video From Class 9 to 12 all Subject Atomic mass & atomic number Definitions With Examples. An Atomic Number (Z) is a number of protons in the nucleus of an atom determines an element’s atomic number. Hybrid Orbitals. The atomic number is equal to the number of protons in the atomic nucleus, which in turn is equal to the number of electrons in the electron shell of the corresponding neutral atom. At the center of each atom is a nucleus that consists of two types of particles called protons and neutrons (and known collectively as nucleons). Carbon's atomic number is 6, and its atomic mass is 12. com with free online thesaurus, antonyms, and definitions. As there are no physical existence of orbital in atoms, it is difficult to measure the atomic radius. Sir William Ramsay discovered helium on earth (1895) Common Compounds: No stable compounds are formed with helium. This website and its content is subject to our Terms and Conditions. Correct answer to the question: An atom of element a has 5 protons. Noun: atomic number 15 A multivalent nonmetallic element of the nitrogen family that occurs commonly in inorganic phosphate rocks and as organic phosphates in all living cells ; is highly reactive and occurs in several allotropic forms. The mass of the atom of a particular isotope relative to hydrogen 1 (or to one twelfth the mass of carbon 12), generally very close to the whole number represented by the sum of the protons and neutrons in the atomic nucleus of the isotope; it is not to be confused with the atomic weight of an element, which may include a number of isotopes in natural proportion. (noun) Three for lithium and 20 for calcium are each an example of an atomic number. the number indicating the order of a chemical element in the periodic system of elements of D. Z (Atomic number) synonyms, Z (Atomic number) pronunciation, Z (Atomic number) translation, English dictionary definition of Z (Atomic number). Effective Atomic Number (EAN) rule 1. The proton number is shown below the chemical symbol, and the mass number is shown above. atomic number synonyms, atomic number pronunciation, atomic number translation, English dictionary definition of atomic number. The mass number ,A, is the total number of protons and neutrons in the atom. See also mass number. Looking for definition of atomic number? atomic number explanation. Definition of atomic number 65 in the Definitions. For the best answers, search on this site https://shorturl. Three percent of the Earth's surface is urban. Definition of atomic radius The atomic radius is the size of the atom, typically measured by the distance from the nucleus of the atom to the electron clouds around the nucleus. We use cookies to enhance your experience on our website, including to provide targeted advertising and track usage. Atomic number example sentences. the number of protons found in the nucleus of an atom of a particular chemical, used as a way of…. In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus. Atomic number is defined, and examples from the periodic table of the elements are provided to help. All atoms of a particular element will have the same atomic number, however they may differ in their number of neutrons and electrons. Louis de Brogllie introduces the wave/particle duality of matter (1921) Traditional (classical) physics had assumed that particles were particles and waves were waves and thats that. Origin of Name: From the Latin word sulfur, meaning brimstone: Date and Place of Discovery: Known to the ancients (referred to as brimstone in the Bible) In 1777 in France it was determined to be an element. In the field of nuclear science, any atomic object whose weight is greater or equal to an electron is considered a particle. Atomic number definition is - an experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines the place of the element in the periodic table. Since it is the electrons that determine how one atom interacts with another, in the end it is the number of protons in the nucleus that determines the chemical properties of an atom. Correct answer to the question: An atom of element a has 5 protons. Different isotopes of an element have the same atomic number, but will have different atomic masses. A chemical element consists of those atoms with a specific number of protons in the nucleus; this number is called the atomic number. What are Isotopes, Isobars, Isotones, Isoelectronic Species. 0107 atomic mass units. 2 words related to atomic number: number, magic number. atomic number 42 - a polyvalent metallic element that resembles chromium and tungsten in its properties; used to strengthen and harden steel. The number of electrons is what makes each element behave a certain way in chemical reactions. It was written the macroscopic cross-section is derived from microscopic cross-section and the atomic number density (N):. View the pronunciation for atomic number. See also: Atomic Mass, Atomic Mass Unit, Atomic Number, Atomic Weight, Magic Number Modern Physics. The atomic number is represented by the symbol Z, and represents the number of protons in an atom. Though individual atoms always have an integer number of atomic mass units, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element. Astatine: Atomic mass number given for longest lived isotope. Rule 1--coordination number principle -in the atomic structure of a mineral, a set number of anions surround each cation--that number is dependent on the ionic radius of the cation and anion--if the atoms are mostly spherical in shape (ionic bond) when combining, spherical geometry can be used to derive the number. By definition, the mass of one mole of an element, or Avogadro's number (6. How to calculate relative atomic mass Introduction Every atom has its own unique relative atomic mass (RAM) based on a standard comparison or relative scale e. What is an Atomic Number? In 1913 the English scientist, Henry Moseley, determined the atomic number of each of the elements and modified the 'Periodic Law' accordingly. The atomic number, Z, is the number of protons in the nucleus. Definition of atomic number 22 in the Fine Dictionary. Because the protons are. The atomic number is equal to the number of protons in an atom's nucleus. Three percent of the Earth's surface is urban. The atomic number refers to the number of protons in the nucleus of a substance. The effect of the spin-spin interaction is noted in Hund's rule #1. Definition from Wiktionary, the free dictionary. atomic number. The atomic mass is in the order of the average number of protons and neutrons permitting the relative abundance of different isotopes. A mole of any atoms has a mass in grams equal to the atomic weight of the element. The mass number ,A, is the total number of protons and neutrons in the atom. atomic number 42 - a polyvalent metallic element that resembles chromium and tungsten in its properties; used to strengthen and harden steel. The number of subatomic particles in an atom can be calculated from the atom's atomic number and mass. An Atomic Number (Z) is a number of protons in the nucleus of an atom determines an element’s atomic number. In other words, 1 amu = 1 gram/mole. Definition of Atomic number. Atomic Size The region of space occupied by an atom's electrons (i. Looking for definition of atomic number? atomic number explanation. Atomic Number is the number of protons present in the nucleus of an element. The sum of the mass number and the atomic number for an atom (A-Z) corresponds to the total number of subatomic particles present in the atom. They are the smallest components of a chemical element, which is a substance that cannot be broken down into simpler material. The mass number (symbol A, from the German word Atomgewicht (atomic weight)), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. And Solved question on the definition. An atom is a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus. 023 × 10 23. This determines what chemical element the atom is. definition of UTC is a stepped atomic time scale implemented in 1972 to permit UT1 to be recovered from broadcast values of UTC for celestial navigation. The weighted average of mass of isotopes of the element can be calculated by. We use cookies to enhance your experience on our website, including to provide targeted advertising and track usage. It has got three isotopes C(12), C(13) and C(14). Only certain isotopes are radioactive and not all radioactive isotopes are appropriate for geological applications -- we have to choose wisely. Still, the size of an atom, even though it is difficult to define and accurately measure, often has significant. , the number of protons). Meaning of atomic number 22 with illustrations and photos. In some number systems there are infinitely many units. The atomic number (number at the top) is the amount of protons and the amount of electrons. The number of protons in the nucleus, Z, is called the atomic number. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius. The atomic number, Z, is the number of protons in the nucleus. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The atomic number is simply the number of protons in an atom. Part of: brine, saltwater, seawater. It is similar to the charge number of the nucleus and is represented by symbol Z. Atomic number is always determined by the number of protons. The number of protons in an atom is given the name atomic number. Definition from Wiktionary, the free dictionary. 2 words related to atomic number: number, magic number. The atomic mass (number at the bottom) is the amount of protons and neutrons added together. The number of protons and electrons an atom has tells us what element it is. atomic number (Z) a number expressive of the number of protons in an atomic nucleus, or the positive charge of the nucleus expressed in terms of the electronic charge. This lesson focuses on an important concept in chemistry and physics known as the atomic number. a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia Scrapingweb Dictionary DB. Definition of Atomic number. of Carbon is 6. Later theories, those of the electrons around the atom, explain why elements in the same period, or group, have similar chemical properties. The number of protons is called the " atomic number " and determines which element the atom is a particle of (and therefore also its chemical properties). Its the most abundant element known in the universe after hydrogen. coordinate lineage subtrahend fourth power arity definite quantity paging second power compound number whole number cardinality multiplier score quotient biquadrate decimal fixed-point number co-ordinate third power record root biquadratic constant multiplier factor augend no. The Scientific Monthly by American Association for the Advancement of Science (1922). Though individual atoms always have an integer number of atomic mass units, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element. 0107 atomic mass units. Elements are defined by the number of protons in the atomic nucleus. Thomson Discovery of the Electron. The mass number (symbol A, from the German word Atomgewicht (atomic weight)), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. atomic number (plural atomic numbers) (physics, chemistry) the number of protons in an atom. Orbital Viewer: A program for drawing orbitals. Standard Atomic Weight The standard atomic weight is the average mass of an element in atomic mass units ("amu"). Atomic Atomic types are types that encapsulate a value whose access is guaranteed to not cause data races and can be used to synchronize memory accesses among different threads. Looking for definition of atomic number 60? atomic number 60 explanation. It is a soft silvery metal which is one of the alkali metals. Pure aluminium is soft and lacks strength, but alloys with small amounts of copper, magnesium, silicon, manganese, and other elements have very useful properties. Quantum Numbers and Atomic Orbitals 1. There are two trends taking place when you look at the elements in the periodic table. atomic number 32 - Dictionary definition and meaning for word atomic number 32 Definition (noun) a brittle grey crystalline element that is a semiconducting metalloid (resembling silicon) used in transistors; occurs in germanite and argyrodite. 02 x 10 23) of atoms, is equal to its atomic mass in grams. Thomson Discovery of the Electron. The number of electrons is equal to the number of protons: the whole entity is thus electrically neutral. Search atomic number and thousands of other words in English definition and synonym dictionary from Reverso. Under this definition, groups 3 to 12 are the transition metals and the f-block lanthanide and actinide series are called the “inner transition metals. Today’s telecommunications and navigation systems utilize continuous timing for their data. 32270 eV) Ref. The mass number (symbol A, from the German word Atomgewicht (atomic weight)), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. The atomic number of an element, also called a proton number, tells you the number of protons or positive particles in an atom. Atomic Structure. Linus Pauling (see 1931) had pointed out that the inert gas atoms grew less inert as their atomic number increased, so that those with higher atomic numbers might be induced to form a bond with fluorine, which was the most active of all elements and the most apt to snatch an electron from unlikely places. What is the atomic number? Every element has a unique atomic number. Antonyms for atomic number. The weighted average of mass of isotopes of the element can be calculated by. Atomic number definition is - an experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines the place of the element in the periodic table. The mass number is slightly higher due to the presence of deuterium and tritium isotopes/. Example: A single 12 C atom has a mass of 12 amu, and a mole of these atoms would have a mass of 12 grams. External Links. Atoms are the basic units of matter. On the periodic table the mass of carbon is reported as 12. Synonyms for atomic number at Thesaurus. Atomic Number Mass Number Atomic Symbol The atomic number, Z, is the number of protons in the nucleus. Atomic number definition, the number of positive charges or protons in the nucleus of an atom of a given element, and therefore also the number of electrons normally surrounding the nucleus. Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid. A given element can have many different isotopes, which differ from one another by the number of neutrons contained. Atomic radius is generally stated as being the total distance from an atom's nucleus to the outermost orbital of electron. The mass of the atom of a particular isotope relative to hydrogen 1 (or to one twelfth the mass of carbon 12), generally very close to the whole number represented by the sum of the protons and neutrons in the atomic nucleus of the isotope; it is not to be confused with the atomic weight of an element, which may include a number of isotopes in natural proportion. The element itself is defined by the atomic number (i. Dictionary Definition of atomic number 53 a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks). This means that each of these atoms has:. So, if one billion atomic bombs had actually rained down at random over the Earth's surface over the last decade, then on average 30 million such bombs would have landed in urban areas. Atomic Number Density. Diagram of the nuclear composition and electron configuration of an atom of nickel-58 (atomic number: 28), the most common isotope of this element. The table is useful because all the elements in a particular column have similar chemical properties. The atomic numbers for every element known to science are listed on the periodic table of the elements. Common Uses: Main filling for blimps (airships) Used to fill balloons. The mass number ,A, is the total number of protons and neutrons in the atom. Atomic mass refers to the average mass of an atom. atomic number. noun: a radioactive element of the alkali-metal group discovered as a disintegration product of actinium. What Is An Atomic Orbital? The 1s, 2s and 3s Orbitals.