GRADE 9 SCIENCE

UNIT 1: ATOMS, ELEMENTS, AND

COMPOUNDS C H A P T E R 1

UNIT TERMS

Use term handout to define all terms for this unit.

1.1 SAFETY IN THE SCIENCE CLASSROOM

Read pages 8-9

Activity 1-1A – Page 9

** Look for 14 things!

Page 10-11

WHIMIS SYMBOLS

Page 12

ExploreMore - Page 13

http://www.sciencelab.com/msds.php?msdsId=9927209

1.2 INVESTIGATING MATTER

WHAT IS MATTER?

Matter is anything that has mass and volume.

Mass is the amount of matter in a substance or object.

Volume is the amount of space a substance or object occupies.

Matter is made up of elements

• Elements are substances that contain one type of matter and

cannot be broken down or separated into simpler substances

• In chemistry, the Periodic Table of Elements is used to organize

elements

PERIODIC TABLE OF ELEMENTS

DESCRIBING MATTER 1. Physical Properties (p. 18)

• Characteristics of matter that are often observed or measured

• Can be either qualitative (observed) or quantitative (measured).

EXAMPLES OF PHYSICAL PROPERTIES

Color

Malleability

Luster

Conductivity

Boiling Point

Melting Point

Texture

Magnetism

Density VIDEO

DESCRIBING MATTER CONTINUED PG. 19

2. Chemical Properties

• Observed when substances react with each other

• Determines a substances usefulness

• Examples

Reactivity

Combustibility

Toxicity

CORE LAB

Physical & Chemical Properties

Page 20

SECTION 1.3 ~ ATOMIC THEORY

THEORY VS. LAW

• A theory is less well supported

than a law.

• Most laws are supported by

different and robust experimental

evidence.

ATOMIC THEORY • The descriptions of matter and how it

behaves.

• Has undergone many modifications as

new facts became available.

EARLY IDEAS….2000 YEARS AGO

Empedocles: matter was

composed of four “elements:”

Earth

Air

Wind

Fire

Aristotle agreed with Empedocles and no one

seriously challenged it for the next 2000 years.

Democritus: eventually a

substance will be cut into a piece

that can no longer be cut. He

called this piece atomos.

THE DEVELOPMENT OF THE ATOMIC THEORY

• John Dalton (1766-1844)

• British schoolteacher and scholar

• He is credited with developing a theory that

was a new way of describing matter

• He suggested that the particles that make up

matter are like small, hard spheres that are

different from different elements

• He defined an atom as the smallest particle of

an element

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, but they 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.

DALTON’S MODEL…BILLIARD BALL MODEL

J.J. THOMSON

• British physicist

• He studied electric currents in gas discharge tubes,

which are related to today’s fluorescent lights.

• He suggested that all atoms must contain electrons

(negative charge)

• His model pictured a positively charged ball with the

negatively charged electrons embedded in it.

THOMSON’S MODEL…RAISIN BUN MODEL

• Pictured positively

charged ball like a

bun with negatively

charged particles

embedded in it like

raisins

ERNST RUTHERFORD (1871-1937)

• He was a scientist from New Zealand (worked at McGill University, Montreal)

• He discovered that atoms have a nucleus

• Nucleus: the tiny, dense, positively charged centre of the atom

• There are two kinds of particles in the nucleus; protons (positive charge) and neutrons (neutral)

RUTHERFORD’S MODEL…

PLANETARY MODEL

NIELS BOHR (1885-1962)

• He proposed that electrons

surround the nucleus in specific

energy levels or shells.

• Each electron has a particular

amount of energy.

BOHR’S MODEL…ORBITAL MODEL

• Rutherford was able to develop Thomson’s model due to the development of new technologies (gold foil experiment)

• The development of cyclotrons and proton accelerators have further developed the model accepted today.

SUMMARY

DEVELOPMENT OF ATOMIC THEORY

WORKSHEET

ATOMIC THEORY DEVELOPMENT RECAP

- CUE CARDS + MARKER

Who described matter as being made up of four

elements; earth, air, wind and fire?

a) Aristotle

b) Democritus

c) Empedocles

d) JJ Thompson

Who agreed with Empedocles theory about

the four elements:

a)Aristotle

b)Democritus

c)Empedocles

d)JJ Thompson

Who described a substance that could no longer

be cut as an atomos?

a) Aristotle

b) Democritus

c) Empedocles

d) JJ Thompson

Who defined the atom as the smallest

particle of an element?

a)Aristotle

b)Democritus

c)JJ Thompson

d) John Dalton

Who said that all matter is made up of

particles called atoms?

a)Aristotle

b)Democritus

c)JJ Thompson

d) John Dalton

Who stated that atoms cannot be created, destroyed or divided into smaller

particles?

a)Aristotle

b)Democritus

c)JJ Thompson

d) John Dalton

What are electrons?

a)Neutrally charged particles

b)Negatively charged particles

c)Particles with no charge

d)Positively charged particles

What are protons?

a)Neutrally charged particles

b)Negatively charged particles

c)Particles with no charge

d)Positively charged particles

What are neutrons?

a)Neutrally charged particles

b)Negatively charged particles

c)Particles with no charge

d)Positively charged particles

Who suggested that all atoms must contain

electrons?

a) Aristotle

b) Democritus

c) Empedocles

d) JJ Thompson

Whose theory does this diagram represent?

a) Aristotle

b) Democritus

c) Empedocles

d) JJ Thompson

Who discovered that atoms had a nucleus?

a) Aristotle

b) Democritus

c) Ernest Rutherford

d) JJ Thompson

Which best describes the nucleus of an atom?

a) Tiny, dense and positively charged

b) Tiny, dense and negatively charged

c) Large, dense and positively charged

d) Large, dense and negatively charged

What are the two types of particles in

the nucleus?

a)Neutrons and protons

b)Neutrons and electrons

c)Protons and electrons

d)None

Who proposed that electrons have a

particular amount of energy and

surround the nucleus?

a) Aristotle

b) Democritus

c) Ernest Rutherford

d) Neil Bohr

INSIDE THE ATOM

• An atom is the smallest particle of an element that

retains the properties of the element.

• All atoms are made up of three kinds of smaller

particles call subatomic particles.

• Three Subatomic Particles:

Protons (positively charged)

Electrons (negatively charged)

Neutrons (no charge)

Subatomic

Particle

Charge Mass Location

Proton (p+) + Large Nucleus

Neutron (n) 0 Large Nucleus

Electron (e-) - Very small Energy

Levels

THE ATOM

MASS

• Protons and neutrons have much more mass than electrons

• This means that when you lift up a large rock, it is the protons and neutrons in the rock that weigh it down

• Protons and neutrons have about the same mass…but they have about 1800 times more mass than an electron

ELECTRIC CHARGE

• The electric charge comes in two types:

Positive

Negative

• Because negative and positive charges attract each

other, protons (positive) and electrons (negative) are

attracted together

• Each proton counts as +1, and each electron counts -

1.

• All atoms have an equal number of protons and

electrons

• This means that the charges add up to zero, making

the atom uncharged or neutral.

BILL NYE: ATOMS

READ PAGES 28 - 29

Test your knowledge:

http://www.chem4kids.com/files/atom_structure.html

QUESTIONS PAGE 33

#15, 17