the atom atomic number and mass, isotopes

The AtomAtomic Number and Mass,Isotopes

ElementsPure substances that cannot be separated into different substances by ordinary processesAre the building blocks of matter112 elements known todayExamples: carbongoldcalcium

Symbols of ElementsUse 1 or 2 letter abbreviations Capitalize the first letter only

Examples:C carbon CocobaltN nitrogenCacalciumF fluorine Br bromine O oxygen Mg magnesium

Symbols from Latin NamesElementSymbolLatin nameCopperCucuprumGoldAuaurumLeadPbplumbumMercuryHghydrargyrumPotassiumKkaliumSilverAgargentumSodiumNanatriumTinSnstannum

% Major Elements in the BodyO65.0 %K 0.34C18.0S 0.26H10.0Na 0.14N 3.0Cl 0.14Ca 1.4Fe 0.004P 1.0 Zn 0.003 Mg 0.50Trace ElementsAs, Cr, Co, Cu, F, I, Mn, Mo, Ni, Se, Si, V

Learning Check Select the correct symbol for each:A. Calcium1) C2) Ca3) CA

B. Sulfur 1) S2) Sl3) SuC. Iron1) Ir2) FE3) Fe

Solution

Select the correct symbol for each:A. Calcium2) Ca

B. Sulfur 1) SC. Iron3) Fe

Learning Check Select the correct name for each:A. N1) neon2) nitrogen 3) nickelB. P1) potassium2) phogiston3) phosphorusC. Ag1) silver2) agean3) gold

Solution Select the correct name for each:A. N2) nitrogen B. P3) phosphorusC. Ag1) silver

Periodic TableRepresents physical and chemical behavior of elementsArranges elements by increasing atomic numberRepeats similar properties in columns known as chemical families or groups

Subatomic ParticlesParticleSymbol Charge RelativeMass Electron e-1- 0

Proton p++ 1

Neutron n0 1

Location of Subatomic Particles 10-13 cm electrons

protons neutrons

10-8 cmnucleus

Atomic Number Counts the number of protonsin an atom

Periodic Table 1 2 3 4 5 6 7 8

11 Na

Atomic Number on the Periodic Table11NaAtomic NumberSymbol

All atoms of an element have the same number of protons11Na11 protonsSodium

Learning Check AT 1State the number of protons for atoms of each of the following:A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protonsB. Sulfur 1) 32 protons 2) 16 protons 3) 6 protonsC. Barium1) 137 protons 2) 81 protons 3) 56 protons

Solution AT 1State the number of protons for atoms of each of the following:A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protonsC. Barium3) 56 protons

Number of ElectronsAn atom is neutral The net charge is zeroNumber of protons = Number of electronsAtomic number = Number of electrons

Mass Number

Counts the number of protons and neutronsin an atom

Atomic SymbolsShow the mass number and atomic numberGive the symbol of the elementmass number 23 Na sodium-23 atomic number11

More Atomic Symbols163165 O P Zn 815308 p+15 p+30 p+8 n16 n35 n8 e-15 e-30 e-

IsotopesAtoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine35Cl37Cl1717 chlorine - 35 chlorine - 37

Learning Check AT 2 Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C14C 6 6 6#P _______ _______ _______ #N _______ _______ _______ #E _______ _______ _______

Solution AT 2

12C 13C14C 6 6 6#P __6___ _ 6___ ___6___ #N __6___ _ _7___ ___8___ #E __6___ _ 6___ ___6___

Learning Check AT 3An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 302) 353) 65

B.Number of neutrons in the zinc atom 1) 302) 353) 65

C. What is the mass number of a zinc isotope with 37 neutrons? 1) 372) 653) 67

Solution AT 3An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 30 B.Number of neutrons in the zinc atom2) 35

C. What is the mass number of a zinc isotope with 37 neutrons?3) 67

Learning Check AT 4Write the atomic symbols for atoms with the following:

A. 8 p+, 8 n, 8 e-___________

B.17p+, 20n, 17e-___________C. 47p+, 60 n, 47 e-___________

Solution AT 4

16OA. 8 p+, 8 n, 8 e- 8

B.17p+, 20n, 17e- 37Cl 17 C. 47p+, 60 n, 47 e-107Ag 47

Learning Check AT 5An atom has 14 protons and 20 neutrons.A.Its atomic number is1) 142) 163) 34

B. Its mass number is1) 142) 163) 34

C. The element is1) Si2) Ca3) Se

D.Another isotope of this element is1) 34X 2) 34X 3) 36X 16 14 14

Solution AT 5An atom has 14 protons and 20 neutrons.A.It has atomic number1) 14

B. It has a mass number of3) 34

C. The element is1) SiD.Another isotope of this element would be3) 36X 14

Masses of AtomsA scale designed for atoms gives their small atomic masses in atomic mass units (amu)An atom of 12C was assigned an exact mass of 12.00 amuRelative masses of all other atoms was determined by comparing each to the mass of 12C An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu.

Atomic MassListed on the periodic tableGives the mass of average atom of each element compared to 12C Average atom based on all the isotopes and their abundance %Atomic mass is not a whole number

Na22.99

Learning Check AT6Using the periodic table, specify the atomic mass of each element (round to the tenths place): A.calcium__________B. aluminum__________C. lead__________D. barium__________E. iron__________

Solution AT6Using the periodic table, specify the atomic mass of each element (round to the tenths place):A.calcium_40.1 amu _ B. aluminum_27.0 amu _ C. lead_207.2 amu_D. barium_137.3 amu_E. iron_55.8 amu__

Calculating Atomic MassPercent(%) abundance of isotopesMass of each isotope of that elementWeighted average = mass isotope1(%) + mass isotope2(%) + 100 100

Atomic Mass of Magnesium Isotopes Mass of Isotope Abundance 24Mg =24.0 amu 78.70%

25Mg = 25.0 amu 10.13%

26Mg = 26.0 amu 11.17%

Atomic mass (average mass) Mg = 24.3 amu Mg24.3