Units 1 and 2 | Chem Regents Review

Homogeneous Mixture

A mixture that is uniform throughout with a distinct pattern.

Pure Substance

A substance that has the same composition throughout and cannot be separated by physical means.

Particle Diagram

A visual representation of the arrangement of particles in a substance.

Chromatography

A technique used to separate mixtures based on differences in their movement through a medium.

Filtration

A method used to separate solids from liquids or gases using a filter.

Distillation

A process used to separate components of a mixture based on differences in boiling points.

Scientific Notation

A method of expressing numbers as a product of a coefficient and a power of ten.

Extensive Property

A property that depends on the amount of material present.

Significant Figures

Digits in a number that contribute to its precision.

Precision

The degree to which repeated measurements under unchanged conditions show the same results.

Accuracy

The degree to which a measurement reflects the true value.

Matter

Anything that has mass and volume.

Element

The simplest form of matter that cannot be broken down into simpler substances.

Compound

A substance formed when two or more elements are chemically bonded together.

Mixture

A combination of two or more substances where each retains its own properties.

Heterogeneous Mixture

A mixture that is not uniform throughout and has no distinct pattern.

S.I. unit

The standard unit of measurement in the International System of Units.

Meter

The base unit of length in the S.I. system.

Liter

The unit of volume in the S.I. system.

Gram

The unit of mass in the S.I. system.

Mass

The amount of matter in an object.

Weight

The force exerted by gravity on an object.

Volume

The amount of space an object occupies.

Density

The mass per unit volume of a substance.

Intensive Property

A property that does not depend on the amount of material present.

Solubility of sodium chloride

40g/100mL of water.

Physical Change

A change that does NOT alter the chemical properties of a substance; examples include cutting paper and phase changes.

Example of Physical Change

Ice melting to become liquid (it's still water!).

Chemical Change

A reaction in which the composition of a substance is changed; properties are not the same as the original matter and energy is produced.

Example of Chemical Change

Firewood burning.

Burning toast

CHEMICAL

Making ice cubes

PHYSICAL

Lighting a candle

CHEMICAL

Spoiling milk

CHEMICAL

Making kool-aid

PHYSICAL

Minimum number of symbols for a compound

2

Understanding Compound Formulas

Within a compound, subscripts tell you the number of each type of atom that is present.

Example of a compound with subscripts

CO2: # carbon atoms 1, # oxygen atoms 2.

Parentheses in compound formulas

If there are parentheses present around two or more atoms, the subscript applies to all atoms within the parentheses.

Example of compound with parentheses

Al(CN)3: # aluminum atoms 1, # carbon atoms 3, # nitrogen atoms 3.

Multiplying subscripts in parentheses

If one of the atoms within the parentheses has a subscript, you multiply this number by the number outside of the parentheses.

Example of compound with multiple subscripts

Fe2(SO4)3: # iron atoms 2, # sulfur atoms 3, # oxygen atoms 12.

Rules for writing element symbols

1) 1st letter is always capitalized; 2) If a second letter exists, it is lower case.

Ag

silver

I

iodine

Al

aluminum

K

potassium

Ar

argon

Kr

krypton

As

arsenic

Li

lithium

Au

gold

Mg

magnesium

B

boron

Mn

manganese

Ba

barium

N

nitrogen

Be

beryllium

Na

sodium

Br

bromine

Ne

neon

C

carbon

Ni

nickel

Ca

calcium

O

oxygen

Cl

chlorine

P

phosphorus

Co

cobalt

Pb

lead

Cr

chromium

Ra

radium

Cs

cesium

Rb

rubidium

Cu

copper

Rn

radon

F

fluorine

S

sulfur

Fe

iron

Si

silicon

Fr

francium

Sn

tin

H

hydrogen

Sr

strontium

He

helium

U

uranium

Hg

mercury

Xe

xenon

Zn

zinc

Watch Glass Evaporation

PHYSICAL separation of homogeneous mixture (solution) by boiling solution, evaporating solvent, and leaving solute

Mantissa

the number out in front in scientific notation, which is between 1-9

SI units

An abbreviation for System International, used in chemistry to measure matter.

SI BASE UNITS

The fundamental units of measurement in the SI system.

Conversion Factors

A mathematical expression that relates two units that measure the same type of quantity.

1 min

60 sec

1000 g

1 kg

1 L

1000 mL

Kilo

A metric prefix meaning multiply the root word by 1000.

Hecto

A metric prefix meaning multiply the root word by 100.

Deca

A metric prefix meaning multiply the root word by 10.

Deci

A metric prefix meaning multiply the root word by 0.1.