Submicroscopic Representations

• Gasses should be shown with lots of empty space between particles.

Standard Colors

Hydrogen = white

Oxygen = red

Nitrogen = blue

Carbon = black/gray

Compounds

Chemical Compounds

Can't be separated physically, only chemically.

Elementary Substances Elemental

Are on the periodic table.

Cannot be physically or chemically separated.

Diatomic nitrogen is still elemental (2 nitrogens bonded together)

Law of Definite Proportions

Properties of elemental substances gained from compounds does not change.

Periodic Table

Columns

Also known as groups.

Rows

Also known as periods.

Metals

Solid at room temp, good conductors

The left 75% of elements.

Nonmetals

Gasses at room temp

Not good conductors.

Metalloids

Combo

Element

Top Left Number

Atomic number

Number of protons.

Atomic Mass

Mass from protons and neutrons.

Substance Composition

H20 (l) The l denotes it's state as liquid.

Subscripts

How many atoms in a molecule.

State of Matter

Denoted by (s), (l), (g), (aq)

Aq means aqueous or dissolved in water.

• Still considered part of a liquid substance.

Compounds

Ionic Compounds

Metal + nonmetal (usually solid).

High melting point (Tm)

Conducts electricity when dissolved in solute.

Are neutral due to electrostatic attraction of cations and anions.

Dissolve in water into their individual ions.

Cation

Positively charged

Anion

Negatively charged.

Molecular Compounds

Nonmetal + Nonmetal

Solids, liquids, or gasses.

Melting point (Tm) varies.

Usually not good conductors.

Diatomic Molecules

N2, O2, F2, Cl2, Br2, I2, H2

Exist naturally in a pair bonded to themselves.

When we show chemical equations, always use the diatomic form!

Cl2 + H2 = HCL

Periodic Table

Element Charges

+1, +2, Variable Charges, +3, +4/-4, -3, -2, -1, 0

Writing Compounds

Molecular Formula

CH4

• Methane

Structural Formula

H-O-H

• Water

The number of lines equals the type of the bond.

• Single bond, double bond, triple bond.

When converting to molecular formula:

1. Write from left to right individually

• If branch in structural formula, put the branch in parenthesis.

1. Combine all atoms and put C first, then H, then others in alphabetical order.

Space Filling

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Ball and Stick

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Nomenclature

Ionic

Write the cation then the anion.

For cations, use the same name as the element:

• Use roman numerals to distinguish the positive charge of the ion.

• Mg2+ = Magnesium

• Cu+ = Copper (I)

• Cu2+ = Copper (II)

For anions, add ide to the root atom it comes from:

• Don't include subscripts in the full name!

Don't include greek prefixes for the number of atoms!

Molecular

If looking at the structural formula, central atoms come first.

• Otherwise, use left to right order or lowest to highest atomic number.

Add ide to the second component

Use greek prefixes for the number of atoms

• Leave off the greek prefixes for the first component if is mono.

CO2 = Carbon Dioxide

SO3 = Sulfur Trioxide

H2) = DiHydrogen Monoxide

Atomic Masses

• Ratio of H to O is 1:16
• 1g of H and 16g of O have the same number of atoms between them.
• 1g of H to 21g of O, O has twice the number of atoms as the H.
• Mass of H2O = mass (H) + mass (H) + mass (O).

Avogadro's Number

_N_A = 6.022 x 10^23 particles/mole

Mole

The amount of substance that contains on N_A of particles.

Molar Mass

1 amu = 1 g/mol

• Mass on periodic table in amu tells us how many grams of an element are in 1 mole.

• If we have 16g O, we have 1 mole, or 6.022 x 10^23 particles.

• N = n + N_A

  • N = number of particles
  • n = number of moles
  • n = m/MM
    • m = mass
    • MM = molar mass