Grade 9 Science

Unit 1: Atoms, Elements, and Compounds

Grade 9 Science

Chapter 1: Atomic theory explains the composition and behaviour of matter.

Grade 9 Science... Unit 1

Lab Safety... A Review

Safety rules and procedures MUST be your top priority.

Know them before you do the lab and use them while doing the lab.

Complete activity 1-1A pg. 9

Laboratory Safety

Safety Rules for the Science Labpages 10-11

General

Glassware

Chemicals

Hot plates and open flames

Electrical equipment

WHMIS... Page 12

Wworkplace

Hhazardous

Mmaterials

Iinformation

Ssystem

Hazard Symbols... Page 13

Dangerous Container

Dangerous Contents

Properties of 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.

Describing Matter

1. Physical Properties pg. 18

Characteristics of matter that are often observed or measured.

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

Color

Malleability

Lustre

Conductivity

Boilingpoint

Melting point

Texture

Magnetism

Density

2. Chemical Properties pg. 19

Observed when substances react with each other.

Determines a substances usefulness.

Reactivity

Combustibility

Core Lab Activity 1-2C pg. 20

Physical and Chemical Properties

Theory vs. Law

A law is better supported than a theory.

Most laws are supported by different and robust experimental evidence.

Theories can change or be modified

Laws rarely change

Atomic Theory

Atomic Theory

The descriptions of matter and how it behaves.

Has undergone many modifications as new facts became available.

An atom consists of a

nucleus

(of protons and neutrons)

electrons in space about the nucleus

The Atom

Inside the Atom

Subatomic ParticleChargeMassLocationProton (p+)+LargeNucleusNeutron (n)neutralLargeNucleusElectron(e-)-Very smallEnergy levels

Early ideas... 2000 years ago

Empedocles: matter was composed of four elements; earth, air, wind, and fire.

460 BC

Democritus: eventually a substance will be cut into a piece that can no longer be cut.

He called this piece atomos.

Aristotle

All matter was composed of four elements

Earth, air, water and fire

Development of Atomic Theory

John Dalton - 1808

He suggested that the particles that make up matter are like small, hard spheres that are different for different elements.

He defined an atom as the smallest particle of an element.

Daltons Model... Billiard Ball Model

J.J. Thomson - 1898

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.

Thomsons Model... Raisin Bun Model

Ernst Rutherford - 1910

He discovered that atoms have a nucleus.

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

Rutherfords Model... Planetary Model

Rutherford was able to develop Thomsons 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.

Rutherfords Experiment

they fired Helium nuclei at a piece of gold foil which was only a few atoms thick.

Gold foil

Helium nuclei

They found that while most of the helium nuclei passed through the foil, a small number were deflected and, to their surprise, some helium nuclei bounced straight back.

Rutherfords new evidence allowed him to propose a more detailed model with a central nucleus.

He suggested that the positive charge was all in a central nucleus. With this holding the electrons in place by electrical attraction

However, this was not the end of the story.

Niels Bohr - 1913

He proposed that electrons surround the nucleus in specific energy levels or shells.

Each electron has a particular amount of energy.

Bohrs Model... Orbital Model

Summary...