Unit 3: Atomic Theory

UNIT 3: ATOMIC THEORY

I. Atomic Theory • Chemical Reaction: the transforming a substance into one or more______. • Up until the end of the 18th century chemists believed that an element couldn’t be further broken down by ordinary chemical means. A. Laws: 1) Law of Conservation of Mass: ______

2) Law of Definite Proportions: ______– Salt- always 39.34 % Na and 60.66 % Cl

B. Dalton’s Atomic Theory 1) All mater is composed of ______2) Atoms of a given element are ______in ______, ______, and other properties; atoms of ______elements ______in ______, ______, and other properties 3) Atoms ______be subdivided, ______, or______. 4) Atoms of ______elements combine in simple whole- number ratios to form ______compounds. 5) In chemical reactions, atoms are______, ______, or ______.

C. Modern Atomic Theory 1) Atomic Structure: a) Atom: the ______particle of an element that ______the chemical properties of the element. b) All atoms consist of ______regions: 1) Nucleus: ______. 2) Electron Cloud: surrounding the nucleus is a ______. 2) Subatomic Particles • Proton:______. – Mass: 1.673 x 10 -27 kg – Symbol:

• Electron: ______. – Mass: 9.108 x 10 -31 kg (found by Robert Millikan) – Symbol:

• Neutron: ______. – Mass: 1.675 x 10 -27 kg – Symbol:

3) Discoveries A) Discovery of the Electron 1) J.J. Thomson’s Cathode ray tube: glass tube where electric current is passed through. Paddle moved, cast shadow, deflected from - 2) Conclusion: ______.

B) Discovery of the Nucleus 1) Ernest Rutherford’s Gold Foil Experiment 2) Bombarded a thin, gold foil with positively charged particles, with high mass 3) Result: ______, so there must be a ______- he called it the ______

– Atoms, Ions, and Isotopes: 1) The Periodic Table: a. Atomic Number: ______– On Periodic Table-elements are placed in order of ______. – Atomic number ______an element – Because atoms are ______- atomic number also indicates ______. b. Mass Number : ______plus ______for a particular atom c. Atomic Mass: ______. d. Molar Mass: the ______of ______of a pure substance (units______) – numerically ______to the ______of the element (found in Periodic Table of Elements) – one mole of Helium has a mass of ~ ______– can be used as a ______. e. Mole (mol) : the ______that contains as many particles as there are ______in exactly ______of carbon-12 – it is a counting unit (______) f. Avogadro’s Number: the ______in exactly ______of a ______substance. – 6.02211367 x 10 23 or 6.022 x 10 23 2) Atoms a. All atomic nuclei are made up of ______and ______. b. The proton and neutron are almost ______in ______and ______. c. atoms are electrically neutral because they contain ______number of ______and ______. d. Atoms of ______elements have ______. e. Atoms of ______element have ______. f. The number of ______identify the atom

3) Isotopes: a. NEUTRONS CHANGE b. ______of an element that are ______alike but______. c. isotopes have the ______number of______, but ______number of______. d. Isotopes have ______. – usually one type of Isotope is predominant

EXAMPLE: 75% 133Cs, 20% 132Cs, 5% 134Cs. What is average atomic mass? ______x______= ______x______= ______x______= ______TOTAL = ______4) Ions: a. ELECTRONS CHANGE b. Used to be atoms, but______were either ______or ______. c. Electrons are______! d. Lose electrons: atom becomes ______negative or ______positive, so there is a ______charge e. Losing 2 electrons, gives a ______charge f. Gain electrons: atom becomes ______negative, so there is a ______charge g. Losing 3 electrons, gives a ______charge

5) Examples: Identify the number of protons, neutrons, and electrons from the following: II. Introduction to the Periodic Table A. Groups or families: – the ______-______of the periodic table – numbered from ______from ______to ______. – each group contains elements with ______chemical properties

B. Periods: – the ______of elements in the periodic table – physical and chemical properties ______somewhat regularly ______a period. Elements that are ______in the ______period are often ______than those ______.

C. Three Major Categories of Periodic Table: 1) Metals: ______. 2) Non-Metals: ______. 3) Metalloids: along the stair–step line.

1) Metals: – an element that is a ______of ______and______. (like Copper) – Malleability:can be ______into thin sheets. – Ductile:can be ______into a ______. – Metallic luster- usually ______or ______(not Au/Cu)

A. Alkali metals: group _____ elements – highly ______-because they want to ______. – don’t exist in nature, by themselves – react ______with ______- K bursts into flames – Electrolytes: K and Na ions needed to ______functions. They ______from the ______to the muscle.

B. Transition metals: group ______C. Alkaline Earth Metals: group ______elements – not as ______as group 1, but still very ______– ______than group 1 and therefore ______.

2. Non-Metals: – an element that is a ______of ______and______. (like Phosphorous) – Many non-metals are ______at room temperature – Gas: ______, ______, ______, ______– Liquid: ______– Solid:______, ______, ______, ______, ______– tend to be______, not______.

A. Halogens: Group ______– ______nonmetals (They want to ______), so ______exit freely in nature. – Antibacterial agents

B. Noble Gases: ______elements found in group ______– All are ______at room temperature – have a ______(______electrons in outer energy level) – Neon, Argon, Krypton, Xenon, are all found in lighting.

3. Metalloids: – element that has ______characteristics of ______and ______characteristics of ______. – ______that separates ______from ______on the periodic table – All are ______at room temperature – Tend to be ______than metals but ______as ______as non-metals – ______of electricity: ability is somewhere ______. – used in______, ______, digital watches, ______, and radios III. Elements • 108 different elements are known, ______occur naturally • ______is most abundant 49%, ______is 26%

H-______Li- ______Na- ______K- ______Rb- ______Cs- ______Fr- ______Be- ______Mg- ______Ca-______Sr- ______Ba- ______Ra- ______B- ______Al- ______C- ______Si- ______N- ______P- ______O- ______S- ______F- ______Cl- ______He- ______Ne- ______Ar- ______Cr- ______Cu- ______Au- ______Ag- ______Zn- ______Fe- ______Ni- ______Sn- ______Pb- ______Br- ______I- ______

IV. Compounds and Mass

A. Compound: – ______.

B. Mass of Compounds: H2O 1) determine the ______of ______element in the compound 1 mole of Hydrogen = ______g or ____g 1 mole of Oxygen = ______g or ____g

2) ______each ______by ______moles of H x ______g/mol = ____ g ____ mole of O x ______g/mol = ____ g

3) Then add: ___g + ____g = _____ g in H2O

Find the mass of NO2 Mass of N =

Mass of O = Mass of N + Mass of O =

Find the mass of C6H12O6

C. Conversions Using Atomic Mass • The ______always goes with ______and it is always ______

• 3.5 mole Carbon, is how many grams?

3.5 mol C x = grams C

• 54 grams H2O, is how many moles?

54 g H2O x = mol H2O

PROBLEMS: *Always figure out the mass of the element or compound first, then convert using the atomic mass

1) How many grams are in 3.89 mol of Calcium? Atoms?

2) How many grams are in 2.05 mol of N2O5? Molecules? 3) How many molecules are in 327 g of H2SO4?