AP Chemistry Unit 1 Guide

What are 2 prefixes, their shorthand, and equivalence?

• Micro (µx) is 10⁶ base units

• Nano (nx) is 10⁹ base units

Calculating with Sig Figs

• Multiplication/Division: Use the least from given

• Addition/Subtraction: Line them up. Use the smallest place value from both numbers. (cut off, but round)

Isotopes vs. Ions

• Isotope: different mass of same element

• Ion: different charge of same element

How to calculate average atomic mass

Summation of the product of mass and percentage, divided by 100

Metalloids? Nonmetals? Alkali Metals? Alkali Earth Metals? halogens? Noble Gases?

• Metalloids: B, Si, Ge, As, Sb, Te

• Nonmetals: Right (including At, Rn)

• Alkali: 1A but H

• Alkali Earth: 2A

• Halogens: Group 17

• Noble Gases: 18

Which element is excpetion to octet?

H/He/Li

Charge Ag? Charge Zn?

• Ag: 1⁺

• Zn: 2⁺

Polyatomic Ions I need to memorize…

• Hydrogen sulfate: HSO4^-1

• Thiocyanate: SCN^-1

• Hypo/ite/ate/per: Bro_x, IO_x and ClO_x

• Permanganate: MnO4-2

• Amide: NH2-1

• Thiosulfate: S2O3-2

• Oxalate: C2O4-2

• Hydrogen phosphate: HPO4-2

• Phosphite: PO3-3

• Borate: BO3-3

How to order elements in a compound

Go with C, then H, then least electronegativity ascending

Properties Based on Bonds

• Melting: Ionic High, Covalent Low

• Dissolving: Ionic Yes, Covalent No

• Conductivity: Ionic Yes, Covalent No

• Ionic hard, covalent soft

• Ionic no smell; covalent yes

Hydrates

Compound with dot and the xH₂O

The 5 Types of Reactions

• Synthesis: A + B → AB

• Decomposition: AB → A + B

• Single Displacement: AB + C → AC + B

• Double Displacement: AB + CD → AD + CB

• Combustion: A + O₂ → CO₂ + H₂O

Empirical vs. Molecular Formulas

• Molecular: true formula per molecule of substance

• Empirical: simplified by division; not true molecular

Percent Comp → Formula

• Assume 100g sample unless told otherwise; if not, divide to get percent AND THEN use. 

• Divide by molar mass to 6 decimal places

• Divide by smallest amount moles

• Multiply as needed to adjust

Coulomb’s Law

Ionic compounds are held together by +/- charges which are strong attractive forces (higher charge = shorter/stronger attraction)

Some elements are diatomic.