Exam 1 Chem

Matter

Composed of atoms; anything that occupies space and has mass

Solid

Rigid with a fixed shape and volume

Liquid

Fixed volume but not shape

Gas

No fixed shape or volume

Pure substance

Made up of a constant composition

Mixture

Made up of a variable composition

Covalent bonds

Sharing of electrons

Ionic bonds

Trading of electrons

Distillation

Separating a component out of a mixture by evaporating it

Physical changes

Changes in form, not chemical composition

Chemical changes

Change one substance into another substance

Intensive properties

Properties that remain the same regardless of how much material is present

Extensive properties

Properties that change depending on how much material is present

Volume

L³

Density

Mass/volume

Accuracy

How close a result is to the “true” value

Precision

How reproducible the result is from trial to trial

Significant figures

All the certain digits in a measurement plus one uncertain digit

Basic equation for conversions

initial units x (desired units/initial units) = desired units

Atomic number

Number of protons

Positive ion

Cation

Negative ion

Anion

Isotopes

Retain the same number of protons as the basic atom, but have different numbers of neutrons

Atomic mass

Average mass of a lot of atoms of one element

Three types of elements

Metals, Metalloids, Nonmetals

Avogadro’s Number

6.022x10^23

Molecular mass

Sum of the average atomic mass of each atom in a molecule

Formula mass

Sum of the average atomic mass of the atoms in the empirical formula of its compound

Electromagnetic radiation

Energy that travels as waves

Wavelength

Peak-to-peak distance (m)

Frequency

Number of complete waves that pass a certain point per unit of time (cycles/second = 1/second = hertz)

Speed of light (C)

2.998x10^8 m/s

Equation for C

C = wavelength x frequency

Name for light that acts as a particle

Photon

Planck’s constant

6.626x10^-34 JS

Equation for energy of a photon (E_photon)

Planck’s constant (6.626x10^-34JS) x frequency

Energy levels

Lyman (UV), Palmer (visible), Paschen (infrared)

Difference in energy level equation

∆E = -2.178x10^-18J (1/n^2final - 1/n^2initial)

Group 1

Alkali metals

Group 2

Alkaline earth metals

Group 16

Chalcogens

Group 17

Halogens

Group 18

Noble gases

Energy levels by color (3-6)

Red, green, blue, purple

Meters per foot

0.3048

Centimeters per inch

2.54

Giga (G) and nanometers

10^9 and 10^-9

Mega and micro (µ) meters

10^6 and 10 ^-6

Kilo and millimeters

10^3 and 10^-3

Deci, centi, and picometers

10^-1, 10^-2 and 10 ^-12