Atomic Theory

1. Given the information in the chart, if a student were to apply heat to equal volumes of all four liquids along with a volume of water, which liquids would boil before the water? A. Q and SB. R and TC. Q and RD. S and T2. If a student is performing an experiment that requires a liquid that has a density less than water, has a higher boiling point than water, and has a distinctive odor, which of the liquids on the chart would be best to use? A. QB. RC. SD. T

Turn in homework (78, 1-6) and test corrections in boxObjectives: Name and describe the mass and charge of the subatomic particles.Find the number of protons, neutrons, and electrons in typical atoms.Catalyst 11/1/10AgendaSubatomic Particle Notes (15-30)Ion and Isotope Notes (30)Homework: Write the Name, Symbol, atomic mass, atomic number, # protons, # neutrons and # electrons of the first 20 elements

Name

1. 2.3....20.Symbol

atomic mass (A)

atomic number(Z)

protons(=Z)

neutrons(=A-Z)

electrons(=Z if neutral )

Homework:Daltons Atomic theorySupport for his theory came when he began looking at the masses of elements that combined with each other. He found that elements combine in simple ratios by mass.

Daltons atomic theoryDaltons atomic theoryall matter is composed of tiny, indivisible particles called atoms.All atoms of the same element are identical in propertiesAtoms of different elements differ in properties.Atoms can neither be created nor destroyed.Atoms of two or more different elements can combine in small whole number ratios to form compounds.Daltons atomic theory2 problems with his theory:Atoms of the same element can have different masses atoms have subatomic particles (electrons, protons and neutrons)So Daltons theory is not completely correct.Two major parts of an atomNucleus (not to scale)Electron CloudThree Major Sub-Atomic Particles Protons Neutrons Electronsa single, relatively large particle with apositive charge that isfound in the nucleus

PROTON (p+) THE PROTON

p+ Fat (heavy) Positive (charge) Doesnt move (lazy)a single, relatively large particle with aneutral charge that isfound in the nucleus

NEUTRON (N) THE NEUTRONN Fat (heavy) Neutral (charge) Doesnt move (lazy)a single, very small particle with anegative charge that isfound in a cloud around the nucleusELECTRON (e-) THE ELECTRON Skinny (very light) Negative (charge) Moves a lot (runs around)e-

Where are they located?Nucleus: Protons and NeutronsElectron Cloud: Only ElectronsAtoms to ElementsWhat makes elements different from one another?The number of protons! Also called the atomic number.Chemical SymbolsElements have a single capitalized letter for their symbol or have two letters-the first is capitalized and the second is lower case.the number of protons in an atomATOMIC NUMBER (Z) The total mass of all of the subatomic particles in an atom (but really # of protons and neutrons)

ATOMIC MASS #(A) Elements are electrically neutral. (They have the same # of p+ and # of e-)ELEMENTSExample: SodiumNa1122.99Atomic # = # of protonsAtomic Mass # = p+ & NRound this number to the nearest whole number!!!Another NotationAtomic # = # of protonsAtomic Mass # = p+ & N

To calculate the number of neutrons, subtract the atomic number (smaller) from the atomic mass number (larger)A Z = # of neutronsEx: How many neutrons does Sodium have?Mass # - Atomic # = #N(You may need to round the atomic #)23 - 11 = 12 NNa1122.99SymbolAtomic MassAtomic NumberHHydrogen11Protons: 1Neutrons: 0Electrons: 1NaSodium2311Protons: 11Neutrons: 12Electrons: 11RheniumRe18675Protons: 75Neutrons: 111Electrons: 75Name

1. Hydrogen2.Helium3....20.Symbol

H

Heatomic mass (A)

1

4atomic number(Z)

1

2protons(=Z)

1

2neutrons(=A-Z)

0

2 electrons(=Z if neutral )

1

2Homework:

Atoms of the same element that differ in charge.(They have the same # of p+, but different # of e-)ION Ex: How many electrons does Sodium have?The atomic number equals the number of protons and the number of electrons. 11 electronsNa1122.99Positive Ions(cations)Negative Ions(anions) Na+ (lost 1 e-) Ca2+ (lost 2 e-) Al3+ (lost 3 e-) Pb4+ (lost 4 e-) H+ (lost 1 e-)

Cl- (gain 1 e-) O2- (gain 2 e-) P3- (gain 3 e-) S2- (gain 2 e-) OH- (gain 1 e-)

If an atom GAINS electrons, its overall charge becomes more negative.If it LOSES electrons, its charge becomes more positiveLearning Check CountingState the number of protons, neutrons, and electrons in each of these ions. 39 K+ 16O -241Ca +2 198 20#p+ ___________________ #no ___________________#e- ___________________

Atoms of the same element that differ in mass.(They have the same # of p+, but different # of N)ISOTOPE Isotopes are CHEMICALLY the SAME as atoms, but DIFFER PHYSICALLY because they have different masses. A few examples of isotopes

Learning Check Counting 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+ _______ _______ _______ #no _______ _______ _______ #e- _______ _______ _______

Answers12C 13C14C 6 6 6#p+ 6 6 6 #no 6 7 8 #e- 6 6 6

One Last Learning CheckWrite the nuclear symbol form for the following atoms or ions:

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

B.17p+, 20n, 17e-___________C. 47p+, 60 n, 46 e-___________ 40So, why do the elements on the PT have masses with decimals??? The periodic table has the average atomic mass of all of the isotopes of a substance

AVERAGE ATOMIC MASS Because of the existence of isotopes, the mass of a collection of atoms has an average value.Boron is 20% 10B and 80% 11B. That is, 11B is 80 percent abundant on earth. For boron atomic weight = 0.20 (10 amu) + 0.80 (11 amu) = 10.8 amu

10B11BAverage atomic mass is calculated by: Mass each isotope and multiply by amount Add calculations for each isotope Divide sum by the total amount