AP Chem Unit 1

Law

What happens

Backed by repeated observations

Theory

Why or how something happens

well tested explanation

can change over time

Tera (T)

10¹²

Giga (G)

10⁹

Mega (M)

10⁶

Kilo (K)

10³

deci (d)

10^-1

centi (c)

10^-2

mili (m)

10^-3

micro (μ)

10^-6

nano (n)

10^-9

Precision

Are results consistent

Accuracy

Is it correct

Random error

unpredictable mistake

Systemic error

consistent mistake

Law of Conservation of Mass

Matter can’t just disappear or reappear

ex. burning wood → turns to ash (mass doesn’t disappear)

Law of Definite Proportions

A compound is always the same recipe

ex. water is always 2 parts hydrogen + 1 part oxygen

Law of Multiple Proportions

Same ingredients, different recipes

ex. C + O = CO or CO₂

→ CO = different proportions than CO₂ but same elements used

→In CO: 12 g of carbon combines with 16 g of oxygen

→ In CO₂: 12 g of carbon combines with 32 g of oxygen

→ The ratio of oxygen masses (16:32) = 1:2, a small whole number ratio

Isotope

Same element, different mass

more neutrons than protons

ex. carbon-12 → 6 protons, 6 neutrons

carbon-14 →6 protons, 8 neutrons

Covalent bonds

when electrons are shared between atoms

Molecule

atoms bonded together

ex. H₂O and O₂

Compound

molecule but with different elements

ex. NaCl

Ionic bonds

one atom transfers electrons to another atom

atom that loses electron becomes a positive ion (cation)

atom that gains electron becomes a negative ion (anion)

Nonmetal + Nonmetal

Covalent

Metal + Nonmetal

Ionic

Diatomic (covalent)

HONClBrIF

Alkali Metals

+1

Highly reactive

Shiny metals

Alkali Earth Metals

+2

Reactive

Transition Metals

Less reactive than groups 1 and 2

Malleable

Halogens

-1

Very reactive nonmetals

Noble gases

Nonreactive

Colorless, odorless gases