Chemistry

THE PARTICLE MODEL OF

MATTER

All matter is made up of extremely tiny

particles.

Each pure substance has its own kind of

particle, different from the particles of other

pure substances.

Particles attract each other.

Particles are always moving.

Particles at a higher temperature move faster

on average than particles at a lower

temperature.

Matter can be classified...

According to its state as a gas, a liquid, or

a solid

According to its composition as a mixture

or a pure substance

Mixtures can be classified by their

properties

If the particles are uniformly scattered, the

mixture is homogeneous

If the particles are NOT uniformly scattered, the

mixture is heterogeneous

CHANGES IN MATTER (properties) - Chemists describe matter in two ways -

Physical Properties

Any property that can be observed or measured

without forming a new substance

Chemical Properties

Any property that describes how a substance

reacts with another substance when forming a

new substance ex. Examples

Reacts with water

Reacts with air

Reacts with pure

oxygen

Reacts with acids

Reacts with other pure

substances

Toxicity

Combustibility

Stability

QUANTITATIVE PHYSICAL

PROPERTIES

Quantitative

A quantitative

physical property is a

characteristic of a

substance that can be

measured numerically

Examples

Melting temperature

Boiling temperature

Density

Viscosity

Solubility

Electrical

conductivity

Heat conductivity

Hardness

QUALITATIVE PHYSICAL

PROPERTIES

Qualitative

A qualitative physical

property is a

characteristic of a

substance that can be

described but might

not be measured

Examples

Colour

Texture

Taste

Smell

State

Crystal shape

Malleability

Ductility

Chemists classify changes in matter into two

categories: Explain what they are

Physical Changes

A substance changes in form but not in chemical

composition; no new substances are formed ex Ice melting/freezing

The taste of chlorinated

water

Tearing a sheet of paper

Chemical Changes

Causes one or more new substances to be

formed; may be difficult or impossible to reverse

Examples

Burning paper

Heating mercury oxide

Rusting

Digestion

Baking/Cooking

Endothermic reactions

A reaction that absorbs energy from its surroundings, usually in the form of heat. In these reactions, the energy required to break the bonds in the reactants is greater than the energy released when new bonds are formed in the products. Examples include photosynthesis, melting ice, and dissolving ammonium chloride in water.

Exotherimiv reations

A reaction that releases energy in the form of heat. The energy is released because the energy required to break the bonds in the reactants is less than the energy released when new bonds are formed in the products. Examples include combustion, explosions, and nuclear fission.

WHAT ARE ELEMENTS?

A pure substance made up of one type of

atom

Each element has its own distinct properties

and cannot be broken down into simpler

substances by means of chemical change

Defined by Antoine Lavoisier (1743-1794)

He also discovered the Law of Conservation of

Mass, which states “in a chemical change, the total

mass of the new substance is always the same as the

total mass of the original substance”.

Examples: hydrogen (H), oxygen (O), carbon

WHAT ARE COMPOUNDS?

Pure substances that are made up of two or

more elements

Compounds can be broken down into

elements again by chemical means

Elements and compounds are both pure

substances

Examples: water (H2O), salt (NaCl), sugar

(C6H12O6)

DALTON’S ATOMIC THEORY

All matter is made up of small particles called

atoms

Atoms cannot be created, destroyed, or divided

into smaller particles

All atoms of the same element are identical in

mass and size

Atoms of one element are different in mass and

size from the atoms of other elements

Compounds are created when atoms of different

elements link together in definite proportions

SOLID SPHERE MODEL

AKA - The Billiard Ball

Model

Discovered by John

Dalton

His theory stated that

atoms are indivisible,

those of a given element

are identical, and

compounds are

combinations of different

types of atoms

THE THOMSON MODEL

AKA - The Plum

Pudding Model

Discovered by JJ

Thomson

He envisioned

negatively charged

electrons stuck in the

positively charged

mass

THE RUTHERFORD MODEL

AKA - The Nuclear

Model

Discovered by Ernest

Rutherford

Almost all of the mass of

the atom was in the

centre, called the nucleus

Tiny electrons orbit the

nucleus

He called the positively

charged particles in the

nucleus protons

THE BOHR MODEL

AKA - The Planetary

Model

Discovered by Neils

Bohr

Electrons rotated around

the nucleus like planets

around the Sun

Bohr suggested that

electrons move around

the nucleus in fixed

pathways called electron

shells

#

THE QUANTUM MODEL

AKA - The Electron Cloud

Model

Discovered by Louis de

Broglie, Erwin Schrodinger

Agreed with Bohr’s theory

of electron levels

Suggested that there was an

area around the nucleus

where electrons were most

likely to be found, called

the “electron cloud”

PARTS OF AN ATOM

Atoms are made up of three types of subatomic

particles

Protons - have a positive charge and are

located in the nucleus

Neutrons - have a neutral/no charge and are

located in the nucleus

Electrons - have a negative charge and orbit

the nucleus

The uncertain location of electrons

ELEMENT CLASSIFICATION

Elements are classified into the following

categories:

State of Matter (solid, liquid, or gas) -

what state the element exists in at room

temperature

Metals/Non-Metals/Metalloids

Groups/Families - vertical columns

Periods - horizontal rows

METALS

Solids at room temperature (except Mercury

- Hg, which is liquid)

Shiny/lustrous

Good conductors of heat and electricity

Malleable - can be flattened into sheets

without crumbling

Ductile - can be stretched into wires

Found of the left side of the staircase line

on the periodic table

NON-METALS

Some gases, some solids, and one liquid

(Bromine - Br is the only liquid)

Dull (not shiny)

Poor conductors of heat and electricity

Brittle, NOT ductile or malleable

Found on the right side of the staircase line on

the periodic table

METALLOIDS

All solids

Most look like metals (shiny, some luster)

but are brittle and don’t bend well

Most have intermediate to good

conductivity (i.e., semiconductors)

Brittle, NOT ductile or malleable

Found along the staircase line on the

periodic table

ATOMIC SYMBOLS

Atomic Number The number of protons in that element Since atoms are neutral, # protons = # electrons. Atomic Mass The total number of all the protons and neutrons in an atom Atomic mass is the average mass of the element’s atoms.

PATTERNS IN THE PERIODIC

TABLE

Size of Atom= ordered in increasing atomic mass, Families or groups - similar chemical properties (elements react the same way when exposed to other substances), Periods (similar atomic stricture (number of e shells)

ALKALI METALS - GROUP #1

Most metals are reactive, but alkali metals

so reactive that many of them require

special storage

Their reactivity is due to an unpaired

electron, that they tend to get rid of by

forming a compound

Alkali Metals reacting with water

Rubidium & Cesium

ALKALINE EARTH METALS -

GROUP #2

Alkaline earth elements react fairly

vigorously with some substances, but are

not as reactive as the alkali metals

Their reactivity is due to the two unpaired

electrons in their outer shell

HALOGENS - GROUP #17

Halogens are naturally found in the form of

compounds because halogen atoms react

vigorously with almost every other element

Like alkali metals, halogens have an unpaired

electron, however, halogens have a tendency to

gain an available electron when they form

compounds

Extremely corrosive and harmful

NOBLE GASES - GROUP #18

Chemists find the noble gases interesting

because they are so unreactive

Noble gases are chemically “stable” because

they do not have any unpaired electrons

They can be forced to react chemically, but

will generally decompose quickly, allowing

the noble gas to separate into single atoms

again

Noble Gases