Chapter 4: Atoms and the Periodic Table

-early theory of matter 4 ingredients 1) ______; cube shaped (made it stable) 2) _____; light weight 3) ______; jagged (why it burned) 4) ______; round (allowed it to flow) - ____- coined in the 5th century B.C. by Greek philosopher Democritus - means “unable to be divided” -1800 John ______- all matter is made of ______- believed atoms were distinguished by their ______- all atoms of the same element will have the same mass - Dalton was not concerned with the composition of atoms, just their mass - matter is made of different atoms - considered the ______for modern atomic theory - 1897 Sir ______(J.J. Thompson) - experiment in a ______tube - electric current from “-“ charged electrode to “+” electrode - brought two electrically charged plates near tube - beam bends towards the “___” plate - proves beam is made of “___“ particles - proved existence of _____ 2

- 1914 Earnest ______- Gold Foil Experiment

1) shot ______particles at a piece of gold foil 2) foil surrounded by ______that turns florescent when struck by an alpha particle 3) a. alpha ( ) particle travels through foil - proves foil is not ______b. particles deflected and truck screen at various angles - showed “+” alpha particles were attracted by “-“ e- c. unexpectedly found some particles reflected _____ - repelled by “+” charge in atom - proved existence of ______charged particle -proton 3

"It was quite the most incredible event that has ever happened to me in my life. It was almost as if you fired a 15-inch shell into a piece of tissue paper and it came back and hit you." E. Rutherford

- 1932 Sir James ______- experiment similar to Rutheford -used ______in place of gold - ______was given off - found radiation weighed as much as the proton, but had no charge - discovered the ______

- 1913 Nels ______- electrons in an atom move in _____ paths around the nucleus much like the planets orbit the sun in our solar system - e- ______is determined by the path - must gain or lose energy to move to different level 4

- 1925 modern model of atom - electrons are more like ______on a vibrating string vs. traveling in a definite path - 1926 Werner ______- exact location of an electron cannot be determined - developed ______- where electrons are more likely to be found - described them in a “cloud” - electron’s location is like blades on a fan - individual blade location cannot be determined, but area of likelihood can be - number of filled levels depends on the number of e- 1st energy level ___e- 2nd energy level ___e- 3rd energy level ___e- 4th energy level ___e- - clouds are made of ______5

4 types of orbitals 1) ____ orbital - single orientation - sphere shaped - lowest energy - holds ___ electrons

2) ____ orbital - dumbbell shaped - 3 orientations (x,y,z) - each of the three p orbitals can hold ___ electrons - holds ___ electrons total 6

3) ____ orbital - 5 orientations - each holds ____ electrons - holds ___ electrons total

4) ___ orbital - 7 orientations - each holds ____ electrons - holds ___ electrons total 7

- ______- electrons in the outermost energy level - determine chemical ______and ______- Ex.- hydrogen vs. neon - hydrogen has 1 e- - 1 valence electron - neon has 10 e- - 2 in the first energy level - 8 in outer (valence) energy level Periodic Table - groups similar elements together - allows for ______- order is based on number of ______- ______- when elements are arranged by proton number, similarities in their properties occur in patterns - lots of different arrangements over time 8

- Dmitri Mendeleev 1896 - arranged by ______- left spaces where needed - correctly ______properties of several of the empty spaces - Henry ______rearranged table based on increasing number of protons - took care of a few discrepancies in Mendeleev’s table - ______- horizontal rows on periodic table - set up several ______including electron arrangement

- Ex.- Hydrogen - 1 electron - electron is in 1st energy level - Ex.- Nitrogen - 7 electrons - 1st energy level, s orbital 2e- - 2nd energy level, s orbital 2e-, p orbital 3e- 2e- + 2e- + 3e- = 7e- 9

- ______or ______- elements in horizontal columns - same number of valence electrons - similar properties - ___- an atom that has gained or lost one or more electrons - has a “+” charge if an electron is lost (______) - has a “-“ charge if an electron is gained (______) - Ex.- Lithium 3e- - 2 in 1st energy level, 1 valence electrons - loses e-….. Li+ - Ex.- Fluorine 9e- - 2 in 1st energy level, 7 in second energy level - gain an electron…..F+ ***electron configuration determines properties*** - ______- (z) - number of ______- number of ______when atom is neutral - never changes for a given element - ______- (a) - number of protons and neutrons - do not include e- because they are so small - to get the number of ______, subtract the atomic ______from the atomic ______A – Z = number of neutrons - ______- atoms of the same element may have different mass numbers - not all are stable - Ex.- Carbon-12, Carbon-13, Carbon-14 98% 1.12% trace 6 protons 6 protons 6 protons 6 neutrons 7 neutrons 8 neutrons 10

- isotope notation 2 forms 1) symbol followed by ______- Ex.- Cl-35 2) symbol with mass and atomic number on left side

- mass of an atom is very small - fluorine’s mass is less than one trillionth of a billionth of a gram - ______- (amu) - used in place of ______- equal to 1/12 the mass of carbon-12 atom - proton and neutron mass is equal to one amu - ______- weighted average - used on periodic table - more common isotope has a larger effect than rarer isotope 11

Classifying Elements (3 classifications) 1) ______- an element that is shiny (luster) and conducts heat and electricity well, also malleable 2) ______- right side of periodic table (except hydrogen) 3) ______- considered non-metals - may conduct electricity

Metals (4 types) 1) Alkali Metals/ group _____ - far ______column on periodic table - soft, shiny, reacts violently with water - not found in nature as ______- too reactive - form compounds

2) Alkaline-earth Metals/ group ______- _____ column from left on periodic table - 2 valence electrons - less reactive than alkali metals - form +2 ions - Ex.- Calcium - shells of many sea creatures - make limestone and marble; coral reef - bones and teeth - Ex.- Magnesium - lightest of all structural metals (airplanes) - enzymes in body

3) Transition Metals/ groups ______- much less reactive than groups ____ and ____ - form “+” ions - many form several possible ions - good conductors of heat and electricity - ______(stretched and shaped) - good for jewelry (shiny)

4) ______Elements - man made - radioactive (always decaying) - make different elements - technetium, promethium, and any element with an atomic number greater than 92 - many make up two rows at bottom of periodic table - allows table to be thin and still have other families line up 14

Non-Metals

- right side of periodic table - groups 17,18 and some elements in groups 13-16 - must form “-“ ions - Carbon - 3 forms 1) ______2) ______3) ______- found in living and non-living things - oxygen, nitrogen, sulfur - form “-“ ion - halogens/ group ______

- 2nd column from right - very reactive - form “-“ ions 15

- uses - Chlorine - Cl gas is very deadly - table salt ______- Fluorine - poisonous yellow gas - fluoride in ______- Bromine - dark red liquid - Iodine - dark purple solid - needed for ______- Noble gases/ group ______- column furthest on the right - exist as single atoms only - inert/unreactive - do not gain or lose electrons - do not form compounds under normal conditions

Semi-conductors/metalloids - 6 elements 1) ______- hard element - added to steel for strength - heat resistant glass 2) ______- makes up 28% of the Earth’s crust (sand) - computer chips 3) ______4) ______- shiny solid that tarnishes in air 5) ______- bluish white solid - shines like metal - fire retardants 6) ______- shiny white solid - classified as non-metals, but have some properties of metals - Ex.- may conduct heat and electricity under certain conditions 17

Counting - ______- (mol) - counting unit - defined as the number of atoms in 12.00 grams of carbon-12 - ______constant- 6.02 x 10 23 (602,213,670,000,000,000,000,000) - number of particles in exactly 1 mol of a ______substance - Ex.- 1 mole of popcorn is 6.02 x 1023 kernels - cover U.S. and be 500 km high - ______- mass in grams of 1 mol of a substance - for elements, the molar mass equals its average atomic mass in amu Calculations 10 gumballs = 21.4 g 50 gumballs = ? 50 gumballs x 21.4 g . = 107 g 10 gumballs - can do the same thing with elements - amount of elements (avagadro’s number) - mass in grams (mass number) - Ex.- mass of 5.5 mol of iron 1) look up mass of iron (Fe) on periodic table Fe = 55.85 5.5 mol Fe x 55.85 g Fe = 307 g Fe 1 mol Fe