AP Chemistry Unit 1: Atomic Structure and Properties

Molecule

Molecule

2 or more same or different atoms bonded together in a specific way

Intramolecular

This force exists between 2 atoms, making them a unit (chemical bond)

Intermolecular

This force exists between 2 molecules and holds them together

Physical Change

change in a state or appearance of matter but not its composition

Physical Properties

Observable, measurable, do not alter the identity of the element when changed

• Color, boiling point, viscosity, magnetism, etc.

Chemical Properties

These are Described in chemical reactions of pure substances

Chemical Change

Change to the composition of matter and making something new

Average atomic mass

A weighted average that takes into account:

1. Every isotope of an element

2. The isotopes’ abundance % in nature

Isotopes

2 or more atoms with the same number of protons but different number of neutrons

Same element but different mass number

Mass Spectroscopy

Used to determine masses and relative abundance of various isotopes

Mass

How much matter is in an object

Volume

Amount of space an object occupies

Extrinsic Property

A property that does not change no matter how much of a sample there is

• Density, boiling and freezing points

Intrinsic Property

A property that depends on how much of a sample there is

Prefix

Goes before a base unit and changes the size of the scale ⇒ makes numbers more workable

Mega

10⁶

Kilo

10³

Deci

10^-1

Centi

10^-2

Milli

10^-3

Micro

10^-6

Nano

10^-9

Pico

10^-12

Dimensional Analysis

Method of using ratio of equivalent values (conversion factors) to convert from one prefix to another or 1 unit system to another

Solid

This state of matter has a definite volume and shape

Liquid

This state of matter has definite volume but no definite shape

• Takes on the shape of part of the container

Gas

This state of matter has no definite volume or shape

• Takes on containers’

Pure Substance

Made up of only 1 type of particle ⇒ Fixed Composition

Element

Made up of one type of atom ⇒ CANNOT be chemically broken down into anything simpler

Compound

2+ Different atoms bonded together in a specific way

Mixture

2+ Different pure substances that are physically mixed together ⇒ keep the identity

• Can have variable composition: different concentrations

Fixed composition

A pure substance that always has the same concentration of particles

Variable Composition

Different concentrations of particles

Homogeneous

Same throughout ⇒ cannot see the different parts (salt water, air, alloys)

Heterogeneous

Distinguishable parts (sand and water, cookies)

Distillation

Capturing evaporated liquid (has to be in one state for both substances)

Filtration

Filtering a solid from a liquid

Chromatography

Technique used to separate a mixture based on their distribution in the mobile vs stationary phase

• Apply compounds to paper, dip in water and compare how much it travels compared to known substances

Atomic Mass

The mass of amu of 1 atom in an element

Avogadro’s Number

6.022 × 10²³

Molar Mass

Mass in grams of 1 mol of an atom or molecules