YEAR 10 SCIENCE

YEAR 10

SCIENCE

CHEMISTRY

Matter

Matter = any material substance with Mass & Volume

Matter

Solid

Liquid

Gas

comes in 3 phases

Solid

Definite Shape

Definite Volume

Liquid

Indefinite Shape – takes the shape of the container

Definite Volume

Gas

Indefinite Shape – takes the shape of the container

Indefinite Volume – can expand and be compressed

Atom the smallest particle making up elements

Sub-atomic Particles

Protons p+ - positive charge, in nucleus

Electrons - e- negative charge, orbiting nucleus

Neutrons n0 – no charge, in nucleus

Drawing an Atom of Carbon

C12.011

6

Atomic Mass

Atomic #

minus Atomic # = # of n0

= # of p+ and # of e-

Carbon has 6 p+ and 6 e-

Carbon has 6 n0

Drawing an Atom of Carbon

6 p+

6 n0

e-

e-

e- e-

e-

e-

PERIODIC TABLEA chart that organises the elements.

It is periodic because the chemical and physical properties of elements can be predicted by their location in the periodic table.

Metals occur on the left hand side of the table and non metals occur on the right. In between are the metalloids. Metalloids have properties of both metals and non-metals.

PERIODIC TABLE

Examples of Elements

H = Hydrogen

C = CarbonO = Oxygen

N = Nitrogen

S = Sulfur

Na = SodiumCa = CalciumK = PotassiumI = Iodine

Cl = ChlorineP = Phosphorus

Example

Chlorine, atomic number 17.

2 electrons fit in the first shell and then it is full.

8 electrons fit in the second shell and then it is full.

There are 7 electrons left so they go in the outer shell

Nucleus

Electron ConfigurationElectrons are arranged around atoms in a series of shells or regions (also called energy levels.Only two electrons can fit in the first shell (closest to the nucleus).No more than eight electrons are usually found in the other electron shells.

An abbreviation

Chlorine, atomic number 17.

The arrangement of electrons can be shortened to:

2, 8, 7

Nucleus

In your workbook complete the following table for the first 20 elements:

Element Atomic Number

Electron configuration

Hydrogen 1 1

Helium 2 2

Lithium 3 2, 1

The periodic table and electrons

Group numbers I to VIII tell us how many electrons are in the outer-most electron shell.

Periods can tell us how many electron shells an element has, for example an element in period 3 has 3 electron shells.

Periodic table

Electrons and reactivityElements with full outer electron shells (Group VIII) are un-reactive.

Elements with outer electron shells that are nearly empty (e.g. sodium has only one electron in its outer most shell) are extremely reactive.

Elements with outer electron shells that are nearly full are also extremely reactive ( e.g. Fluorine has 7 electrons in its outer most shell)

Elements and compounds and mixtures.

Elements contain only one kind of atom.Compounds are made of several atoms chemically joined together.Mixtures contain different compounds but they are not joined together.

Soft drink is a mixture

Chemical formulas are not used to describe mixtures. Carbonated drinks are a mixture of water, sugars and flavorings with carbon dioxide gas dissolved in the water

Think about this – What makes up a soft drink?

Think about it in terms of elements– What is the chemical formula for water– Water is a molecule (compound)

What makes the drink fizz– Carbon Dioxide

What is the sugar made from– More complex compound

Compounds

Compounds - 2 or more elements chemically

combined to form a new substance with

new properties Properties – The way a

chemical substance looks and behaves

Compounds

Compounds – are made of 2 or more different atoms

combined to form Molecules

H + O H2O =

HO

HChemical formula lists the number of different atoms

in a single molecule

Structural formula shows the arrangement of the

atoms in a single molecule

Molecules

Glucose Sugar

C6H12O6

Chemical formula

C

H

OH

C C

C

C CH

HH

H

H

HOH

O

OH

HOOH

Structural formula

Compounds

Inorganic

Compounds or Organic

Compounds • usually don’t contain Carbon• generally come from the earth• generally simple molecules

• always contain C & H and usually O, N, sometimes S & P• originate in organisms• generally complex molecules

Examples of Inorganic Compounds

H + O = H2O = Water

H + Cl = HCl = Hydrochloric Acid

C + O = CO2 = Carbon Dioxide

Na + Cl = NaCl = Common Table Salt

Examples of Organic Compounds

C, H + O Carbohydrates = Sugars, starches & cellulose

C, H + O Lipids = Fats & Oils

C, H, O, N, & sometimes P + S

Proteins

C, H, O, N, + P Nucleic Acids – DNA & RNA

IONS

We already know:Atoms are neutral - no chargeElectrons are on the outside of atomsAtoms react by exchanging or sharing

electrons

When atoms exchange electrons, ions are formed.

What are ions? Atoms with a charge Have an unequal number of protons and

electrons. This occurs because atoms either gain or lose

electrons. If atoms gain electrons it means they become

more negative since each extra electron is an extra negative charge.

If atoms lose electrons it means they become more positive since the loss of an electron is a loss of a negative charge.

Have the following ions gained or lost electrons?

ION GAIN LOSS

F-1

Ag+1

O2-

Al3+

N3-

What happens to the atom Example: sodium, Na The atom Na becomes the ion Na1+

Looking at the periodic table we can see that sodium has 11 protons. We know that the atom Na has 11 electrons. Therefore the number of + charges (protons) is the same as the number of – charges (electrons).

The ion Na1+ is formed when sodium loses 1 electron, meaning it now has only 10 electrons. The number of protons in the nucleus has not changed. Therefore the ion Na1+ has 11 + charges (protons) and only 10 – charges (electrons). The overall charge is +1.

The charge of an ion is always written at the top (superscript)

How can you tell?

Method 1: The periodic table

GROUP CHARGEI +1II +2III +3IV +4 or -4V -3VI -2VII -1VIII None

How can you tell?

Method 2: look at the electronsChemical reactions occur because

elements will try to have a full outer electron shell with 8 electrons in it.

Atoms of elements that have nearly empty electron shells will lose those electrons.

Atoms of elements that have nearly full electron shells will gain electrons to fill the shells.

Example:

Number of electrons in outer shell

Electrons gained or lost

1 1 lost2 2 lost3 3 lost4 4 lost or 4 gained5 3 gained6 2 gained7 1 gained8 none

Physical & Chemical ChangeHow do you know that a chemical reaction

has taken place?

PHYSICAL CHEMICALChanges shape A permanent colour

changeBreaks into smaller

piecesA gas is given off

Dissolves Change in temperature

Mixed with another substance

Precipitate forms

Changes state One metal is deposited on another

No new substances formed

New substances are formed

Temperature changesEndothermic reactions- absorb heat and

as a result the temperature falls.

Exothermic reactions- release heat and as a result the temperature rises.

YEAR 10 CHEMISTRY

REACTION TYPES

Symbols used in Chemical reactions

(s) solid

(l) liquid

(g) gas

(aq) aqueous (a solution: means the substance is dissolved in water)

COMBINATIONJoining reactionTwo or more substances combine to form

a new substance. X + Y XYExample:C (s)+ O2(g) CO2(g)

DECOMPOSITIONBreak down reactionsOpposite of combination reactions.XY X + YExample:2NaN3 (s) 2Na(s) + 3N2(g)

PRECIPITATIONTwo solutions mixed together make a

solid.Example;AgNO3(aq) + NaCl(aq) AgCl (s) +

NaNO3(aq)

COMBUSTIONUses oxygen, happens quickly and

produces heat and light.Example:CH4 (g) + 2O2(g) CO2 + 2H2O(l)

NEUTRALISATIONAcid + base reactionProduces salt and water.Example:HCl(aq) + NaOH(aq) NaCl (aq) + H2O (l)

DISPLACEMENTOne metal deposits on another. A metal

solution reacts to become the pure solid metal.

Example:Zn(s) + CuSO4(aq) ZnSO4(aq) +

Cu(s)

Classify the following reactions: C3H8(l) + 5O2 3CO2(g) + 4H2O(l)Combustion HNO3(aq) + LiOH(aq) LiNO3 (aq) + H2O (l)Neutralisation CuSO4 + 2NaOH(aq) Na2SO4(aq) +

Cu(OH)2(s)Precipitation 2Na(s) + Cu(NO3)2 2NaNO3 (aq) + Cu(s)Displacement KMnO4(s) KMnO2(s) + O2(g)Decomposition N2(g) + O2(g) 2NO(g)Combination