1 Matter, Mass, Molecules, Moles, & Motion

Question 1

Atomic Weight

Answer 1

Atomic mass unit (AMU) designation of weight
1 AMU = 1 / (6.02 x 10^23) g/mol
1 Mol = 6.02 x 10^23
1 AMU element = grams when 1 Mol present
1 Mol Carbon = 12g

Question 2

Molecular Weight

Answer 2

Add atomic mass of all elements present in molecule

C6H12O6 = (6x12) + (1x12) + (16x6) = 180g

Question 3

Atomic Number

Answer 3

Number of protons in the nucleus of an atom
Does not change - would change the element
Hydrogen 1 proton (+)
Calcium 20 protons (+)

Question 4

Atomic Mass

Answer 4

Total number protons and neutrons in the nucleus
Nitrogen 14.007
7+ protons 7 neutrons (neutral)

Question 5

Isotope

Answer 5

Same element (# protons) w/ different number neutrons
Different atomic mass
Nitrogen-15
7+ protons 8 neutrons
Atomic mass = 14.007

Question 6

H2O Properties

Answer 6

Universal solvent d/t dipole nature
Less dense when frozen - ice floats
Amphoteric - acid & base
High latent heat - stores more heat per unit volume than other substances and releases heat slowly
High vaporization heat - large amount heat required to break hydrogen bonds and the heat carried off as H2O vapor
Cohesive (molecules tend to stick together) AND adhesive (tend to stick to surfaces w/ polar groups)
Dissociates into H+ & OH¯
Attraction & repulsion forces among H2O molecules - produces space between for gas molecules
HIGH ↑BP ↑MP

Question 7

Atom

Answer 7

Smallest fraction of an element w/ element characteristics
“Building block”
Composed of subatomic particles - protons, neutrons, electrons

Question 8

Element

Answer 8

Substance that cannot be separated into simple substance
C, O, & N
Oxygen exists as diatomic element (O2)

Question 9

Molecule

Answer 9

Two or more atoms chemically joined together
H2, N2, O2
Same elements
Exist in nature bound to self

Question 10

Compound

Answer 10

Molecule that contains at least 2 different elements

C6H12O6 (glucose)

Question 11

Physical Change

Answer 11

State of matter
Solid - less energy, densely packed, slowest
Liquid - more energy, less dense, faster
Gas - most energy, moving & dispersing, fastest

Question 12

Chemical Change

Answer 12

Change in matter composition
Bonds broken & new bonds formed → new chemical entity produced w/ different properties/reaction
CO2 + H2O → H+ + HCO3

Question 13

Gravity

Answer 13

Attraction b/w all objects and force r/t
Smaller distance = ↑ force
1 / d^2

Question 14

Weight

Answer 14

Gravitational force experienced by body (mass) on earth

Relative to gravitational force applied to mass

Question 15

Mass

Answer 15

Unchanged

↑ mass ↑ gravity reaction ↑ weight

Question 16

Adhesion

Answer 16

Interaction b/w unlike molecules
H2O molecules attract to the glass
Pulling down & raising up along sides
CONCAVE

Question 17

Cohesion

Answer 17

Interaction b/w like molecules
Exhibit mutual attraction force
↑ distance ↓ force 
CONVEX
Liquid pulls away from glass towards other H2O molecules

Question 18

Octet Rule

Answer 18

1st shell 2e¯
2nd & 3rd shell 8e¯
Molecules react w/ other molecules to fill outer (valence) shell and become more stable

Question 19

Covalent Bonds

Answer 19

Shared e¯ pair b/w 2 atoms
Overlap orbitals or e¯ clouds to satisfy octet therefore more stable
Equal = non-polar
Unequal = polar

Question 20

Density

Answer 20

D = M / V
1Mol = 22.4L
Gram molecular weight or mole
Liquids measured in grams/cm^3
(cm^3 = mL)
Gas/vapors:  MW/GMV or g/L

Question 21

Avogadro’s Number

Answer 21

Equal volume gas at STP have same number molecules

1Mol = 6.02 x 10^23 molecules

Question 22

Specific Gravity

Answer 22

Liquid or gas weight of unit volume
Compared to standard volume H2O or dry air
Ratio b/w two densities
Liquid MW / H2O MW
Gas MW / Dry air MW
↓specific gravity = lower density ↓resistance

Question 23

Halogens

Answer 23

Extremely reactive d/t out shell not filled
7e¯ valence
Highly electronegative
Form salts w/ Na+
Acids when combined w/ H+
F, Cl, Br, I

Question 24

H2O Properties

Answer 24

Universal solvent d/t dipole & polar properties
Able to dissolve polar substances
High melting & boiling point
Less dense when frozen than in solid state (ice floats)
Amphoteric - acid & base properties
Water dissociates into H+ & OH¯ (contributes to acid/base balance)
Tetrahedral shape to maximize distance b/w e¯ pairs
Attractive and repulsive forces among H2O molecules - makes space b/w molecules for gas
High latent heat - stores more heat per unit volume & releases heat slowly
High vaporization heat - large amount heat required to break hydrogen bonds & heat carried off as vapor
Cohesive AND adhesive