SNC2DGrade 10 Science - academic

Chemistry review: grade 9

What is “Matter”?

Matter = any substance with Mass & Volume (takes up space)

Examples?

Properties of matter A physical property is a characteristic of a substance that can be

observed or measured without changing the substance’s composition (i.e. ice is still water). Some physical properties:

1 – colour2 – texture (fine, coarse, smooth, etc)3 – odour (odourless, spicy, sharp, etc)4 – luster (shiny, dull, vitreous, etc)5 – taste (sweet, sour, bitter, etc)6 – hardness (measure of resistance of been scratched. A harder material will scratch a softer one. Diamond will scratch glass. Nail will scratch a chalk)7 – Solubility (ability of a substance to dissolve in a solvent like water. Salt is soluble and pepper is insoluble)8 – Viscosity (how easily a liquid flows. Maple syrup is more viscous (“thicker”) than water9 – state (whether is solid, liquid, or gas at room temperature)10 – melting and boiling points (temperature which substances change state. Liquid water changes to vapour at 100 0C and become solid ice at 0oC)

Physical Properties of Matter

Properties of matter

A description / statement of whether or not a substance reacts with another substance to form a new compound is a chemical property of matter. Examples below:

Chemical Properties of Matter

1 – Combustibility: ability of a substance to react with oxygen to produce carbon dioxide, water, and energy when exposed to flame. Gasoline is combustible (= flammable or inflammable). Water is non-flammable.

2 – Reaction with acid: ability to react with acid. Limestone (chalk) reacts with acid producing bubbles of gas.

Elements

Each row in the periodic table is known as Periods. The columns, which consist of elements having similar chemical properties, are known as Groups or Families.

The periodic table has 7 periods and 18 families.

METALS NONMETALS METALLOIDS

Shine, usually grey (except gold and copper), and solid (except mercury). They are good conductors of heat & electricity. Can be hammered into sheets without breaking.

Dull, different colours , solid, gases, or liquid. Not good conductors. Easily broken.

An element having both metallic and nonmetallic properties. They are usually good semiconductors

(web.buddyproject.org/.../web017/ images/periodic%20table.JPG)

HalogensAlkali metals

Noble gases

Examples of chemical groups (families)

ATOM

Atom is the smallest amount of an element

Atomic model

Electrons

nucleus with ProtonsNeutrons

SUBATOMIC PARTICLESSUBATOMIC PARTICLES

Particle

proton

neutron

electron e-

Charge

positive charge

negative charge

no charge

1

1

0(almost 2000

times lighter than proton or

neutron)

Mass

p+

n

Atomic Number

Is the number of protons in an atom.

by association, it’s also the number of electrons, since atoms are neutral (charge zero)

2.4

Practice questions

State the number of protons for atoms of each of the following:1. Nitrogen a) 5 protons b) 7 protons c) 14 protons

2. Sulfur a) 32 protons b) 16 protons c) 6 protons

3. Bariuma) 137 protons b) 81 protons c) 56 protons

Answers

State the number of protons for atoms of each of the following:1. Nitrogen b) 7 protons 2. Sulfur

b) 16 protons

3. Bariumc) 56 protons

Mass Number (different from atomic mass)

Mass number = number of protons + number of neutrons

Atomic number and atomic mass in the Periodic Table

11Na

22.99

Atomic Number

Symbol

Atomic Mass

Protons =11

Electrons =11

Protons +neutrons =22.9

(round off the number to 23)

Neutrons =23-11=12

Atomic number = number of protons in nucleus

Mass number = number of protons + number of neutrons

= atomic number + number of neutrons

Cl3517

Mass Number

Atomic NumberElement Symbol

Standard atomic notation

17 protons17 electrons18 neutrons (= 35 -17)

Subatomic Particles in Some Atoms

16 31 65

O P Zn8 15 30

8 p+ 15 p+ 30 p+

8 n 16 n 35 n8 e- 15 e- 30 e-

So far: numbers of subatomic particles

Now: arrangement

Protons and neutrons: nucleus

Electrons The circles are NOT orbits. The electrons are NOT moving around the nucleus along the circles, like planets around the sun. It is impossible to know how an electron is actually moving in an atom .

Instead, the circles represents regions called orbitals (or shells) with different energy levels. The two electrons on the circle closest to the nucleus have the lowest energy and the eight electrons on the next circle have a higher energy.

2-8-8 rule*

Building in which next floor up can only be filled if the lower floor is filled

* The maximum number of electrons that can occupy each shell has been determined for the 20 first elements

ELECTRON ORBITALSELECTRON ORBITALS

Electrons are arranged in Energy Shells/

or Valence Shells around the nucleus of

an atom.• first shell a maximum of 2 electrons

• second shell a maximum of 8

electrons

• third shell a maximum of 8

electrons

BOHR - RUTHERFORD DIAGRAMSBOHR - RUTHERFORD DIAGRAMS

Bohr – Rutherford diagrams are simple drawings

that show the numbers and locations of protons,

neutrons and electrons in an atom (or ion).

Nitrogen 7p+

7n0oo o

oo

o

o

N7

14

BOHR - RUTHERFORD DIAGRAMSBOHR - RUTHERFORD DIAGRAMS

Draw the Bohr - Rutherford diagrams for the atoms of the following elements: Oxygen and Chlorine

O Cl8 17

16 35a) b)

8 p+

8n0

o

o

o

o

o

o

o17 p+18 no

o

o

o

o

o

o

oo

oo o

o

o o

o

oo

SUMMARYSUMMARY

1. The Atomic Number of an atom = number of

protons in the nucleus.

2. The Mass Number of an atom = number of

Protons + Neutrons in the nucleus.

Atomic Mass = mass of protons and neutrons and electrons of the atom

3. The number of Protons = Number of Electrons.

4. Electrons are located around the nucleus in energy shells.

5. Each shell can only carry a set number of electrons.

ATOMIC STRUCTURE MODELSATOMIC STRUCTURE MODELS

There are several ways to represent the

atomic structure of an element or compound:

2. Electronic Configuration

1. Bohr - Rutherford Diagrams

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

With electronic configuration elements are

represented numerically by the number of

electrons in their shells and number of shells. For

example;

NNitrogen

7

142 in 1st shell

5 in 2nd shell

configuration = 2 , 5

2 + 5 = 7

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

Write the electronic configuration for the following elements;

Ca O

Cl Si

Na20

40

11

23

8

17

16

35

14

28

B11

5

a) b) c)

d) e) f)

2,8,8,2 2,8,1

2,8,7 2,8,4 2,3

2,6

Ion (charged atom)

Ions (charged atom)

Formation of Ionic Compounds

Ionic Compound (metal + non metal)

Write down the name of the first element;

Write down the name of second element and add “IDE”.

e.g. Magnesium + oxygen magnesium oxide

BaCl2 barium chloride

K2O potassium oxide

BaCl2 K2O