UNIT 1: CHEMISTRY

Grade 9 Science

Unit 1:Chemistry

Chemistry=> The scientific study of matter, its properties and interaction with other matter.

Chemical=> any substance used or produced in a chemical process. It is anything that has mass. Some examples are water, table salt, vinegar...etc

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.

3 States of Matter

Matter can be classified as:1. an Impure substance : made of

two or more substances.Ex. Mixture (ex. Sand in water-

can distinguish between substances) or Solution (ex. Salt dissolved in water- appears to be all one substance)

2. a Pure substance (made of one substance) - All samples taken from a pure substance will have the same characteristics (ex melting point, colour, odour, ....).

2 Types of Pure Substances1. Element 2. Compounds

ELEMENTS

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.

(Ex. Hydrogen- H2, Oxygen- O2 ) http://www.youtube.com/watch?v=d0zION8xjbM&safety_

mode=true&persist_safety_mode=1

Compounds

Compound pure substance that consists of two or more elements combined in a fixed proportion. -It can be broken down into two or more simpler substances by means of a chemical changes.

Water (H20) Sugar (C12H22011) Salt (NaCl)

Questions 1, 2, & 3 Pg. 19

Describing Matter

1. Physical Properties pg. 18

Characteristics of matter that are often observed or measured.

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

Physical Properties of Matter1. Color2. Malleability

(bend)3. Lustre (shine)4. Conductivity

(electricity)5. Boiling point6. Melting point7. Texture8. Magnetism9. Density

2. Chemical Properties pg. 19

Observed when substances react with each other.

Ex. When you light a magnesium sparkler, it glows a bright white colour (chemical change). Burning brightly is a chemical property of magnesium.

http://www.youtube.com/watch?v=5UJTR-LA1z4&feature=related

Determines a substances usefulness.

Ex. Jewelry is often made of gold. This metal doesn’t react easily with air or water, so they will not deteriorate over time.

http://www.youtube.com/watch?v=6WjBM-ZgysQ&safety_mode=true&persist_safety_mode=1

Physical Change

When the appearance of a substance changes, but chemically the substance is the same.

The molecules do not change and no new matter is formed

Examples of physical changes: evaporating, melting, freezing, sublimating (Solid Gas ), when substances are mixed and something dissolves.

Chemical Change

When a chemical reaction takes place. The substances produced during a chemical

reaction are different from the original substances. Energy is involved in all chemical reactions (heat

is given off) Evidence of a Chemical Change:-solid precipitate is formed in a liquid-heat or light is given off-A gas is produced- A colour change occurs- http://www.youtube.com/watch?v=uCwHzTsx5yY&

feature=related

Chemical Properties of Matter

1. Reactivity (how reactive it is)

2. Combustibility (how easy it is to catch on fire!)

3. Toxicity (how toxic it is)

Atomic Theory

The description of matter and how it behaves.

Has undergone many modifications as new facts became available.

Atomic Theory

Early ideas... 2000 years ago

Empedocles: matter was composed of four “elements”; earth, air, water, and fire.

Democritus: eventually a substance will be cut into a piece that can no longer be cut. He called this piece atomos.

Dalton’s Atomic Theory

1. All matter is made of small particles called atoms.

2. Atoms cannot be created, destroyed, or divided into smaller particles.

3. 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.

4. Compounds are created when atoms of different elements link together in definite proportions.

Atoms and Molecules

Atom the smallest particle of matter.

Molecule: a particle that is formed when two or more atoms are joined together Examples:

O2 => (two oxygen atoms)H20=>(Two hydrogen and one oxygen)

C6H12O6 ( six carbon, twelve hydrogen, and six oxygen)

Compounds contains atoms of at least two different elements

Therefore, some molecules contain only identical atoms ; these are molecules of an element.

Ex. O2 => (two oxygen atoms)=> Molecule of element

Other molecules contain different atoms of different elements; molecules of a compound.

Ex. H20=>(Two hydrogen and one oxygen)=> molecule of compound

Theory vs. Law

A theory is not as well supported as a law.

Most laws are supported by a large amount of experimental evidence that is varied.

CHEMICAL FORMULA

Chemical symbol is a way of representing elements by using a single capital letter or a capital letter followed by a small letter.

Examples: Hydrogen => HCalcium => Ca

Chemical formula is the combination of chemical symbols that represent a chemical compound.

-it indicates the kinds of elements in a compound and what proportions they are present in.

Example: Chemical formula for ozone O3

This indicates that ozone contains oxygen. There are 3 atoms of oxygen

In compounds, atoms of two or more different elements combine in a specific proportion. That is, a certain number of atoms of one element join together in a definite fixed ratio with atoms of another element.

INSIDE THE ATOM

Atoms are the smallest particles of an element and are the building blocks of many substances.

Atoms are composed of three kinds of subatomic particles: (analogy: houses form communities, but houses have there own components, bedroom, kitchen, bathroom...) Protons Electrons Neutrons

Proton: positively(+) charged particles found in the nucleus of an atom.

Each of the different elements contains atoms that differ in their number of protons.

Electron: negatively(-) charged particle found orbiting around the nucleus very rapidly.

Neutron: neutrally charged particle also found in the nucleus of an atom.

http://www.youtube.com/watch?v=lP57gEWcisY&safety_mode=true&persist_safety_mode=1

Important Facts About Atoms: The number of protons and the

number of electrons in the atom are equal. Therefore, atoms have no charge.

Nucleus of an Atom

Nucleus of the atoms are positively charged because they contain the protons.

The nucleus of the atom is very tiny (protons and neutrons are held tightly together in the nucleus).

Almost all of the mass of the atom is made up by the nucleus

John Dalton (1766-1844)

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.

Dalton’s Model... Billiard Ball Model

J.J. Thomson (1856-1940)

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

Ernst Rutherford (1871-1937)

He discovered that atoms have a nucleus.

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.

Review questions for Chapter 1 Quiz

P 34 #1,4-11,13,15