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+ p+ - positive charge, in nucleus Electrons - e - negative charge, orbiting nucleus Neutrons n0 n0 – no charge, in nucleus

Drawing an Atom of Carbon C Atomic Mass Atomic # minus Atomic # = # of n0n0 = # p+ p+ and # of e-e- Carbon has 6 p + and 6 e - Carbon has 6 n 0

Drawing an Atom of Carbon 6 p + 6 n 0 e-e- e-e- e-e- e-e- e-e- e-e-

PERIODIC TABLE A 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= Carbon O= Oxygen N= Nitrogen S= Sulfur Na= Sodium Ca= Calcium K= Potassium I= Iodine Cl= Chlorine P= Phosphorus

Example Chlorine, atomic number 17. Chlorine, atomic number 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 Configuration Electrons 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. 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 Hydrogen11 Helium22 Lithium3 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 Periodic table

Electrons and reactivity Elements 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 - 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 H 2 O = H O H Chemical 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 C 6 H 12 O 6 Chemical formula C H OH CC C CC H H H H H H OH O O H H O OH 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 = H 2 O = Water H + Cl = HCl = Hydrochloric Acid C + O = CO 2 = 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 charge Atoms are neutral - no charge Electrons are on the outside of atoms Electrons are on the outside of atoms Atoms react by exchanging or sharing electrons Atoms react by exchanging or sharing electrons When atoms exchange electrons, ions are formed. When atoms exchange electrons, ions are formed.

What are ions? Atoms with a charge Atoms with a charge Have an unequal number of protons and electrons. Have an unequal number of protons and electrons. This occurs because atoms either gain or lose 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 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. 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? IONGAINLOSS F -1 Ag +1 O 2- Al 3+ N 3-

What happens to the atom Example: sodium, Na Example: sodium, Na The atom Na becomes the ion Na 1+ The atom Na becomes the ion Na 1+ 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 Na 1+ 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 Na 1+ 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) The charge of an ion is always written at the top (superscript)

How can you tell? Method 1: The periodic table GROUPCHARGE I+1 II+2 III+3 IV +4 or -4 V-3 VI-2 VII VIIINone

How can you tell? Method 2: look at the electrons Chemical reactions occur because elements will try to have a full outer electron shell with 8 electrons in it. Chemical 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 empty electron shells will lose those electrons. Atoms of elements that have nearly full electron shells will gain electrons to fill the shells. 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 lost 2 2 lost 3 3 lost 4 4 lost or 4 gained 5 3 gained 6 2 gained 7 1 gained 8none

Physical & Chemical Change How do you know that a chemical reaction has taken place? How do you know that a chemical reaction has taken place?

PHYSICALCHEMICAL Changes shape A permanent colour change Breaks into smaller pieces A 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 changes Endothermic reactions- absorb heat and as a result the temperature falls. Endothermic reactions- absorb heat and as a result the temperature falls. Exothermic reactions- release heat and as a result the temperature rises. Exothermic reactions- release heat and as a result the temperature rises.

YEAR 10 CHEMISTRY REACTION TYPES

Symbols used in Chemical reactions (s) solid (s) solid (l) liquid (l) liquid (g) gas (g) gas (aq) aqueous (a solution: means the substance is dissolved in water) (aq) aqueous (a solution: means the substance is dissolved in water)

COMBINATION Joining reaction Joining reaction Two or more substances combine to form a new substance. Two or more substances combine to form a new substance. X + Y XY X + Y XY Example: Example: C (s)+ O 2(g) CO 2(g)

DECOMPOSITION Break down reactions Break down reactions Opposite of combination reactions. Opposite of combination reactions. XYX + Y XYX + Y Example: Example: 2NaN 3 (s)2Na(s) + 3N 2 (g)

PRECIPITATION Two solutions mixed together make a solid. Two solutions mixed together make a solid. Example; Example; AgNO 3 (aq) + NaCl(aq)AgCl (s) + NaNO 3(aq)

COMBUSTION Uses oxygen, happens quickly and produces heat and light. Uses oxygen, happens quickly and produces heat and light. Example: Example: CH 4 (g) + 2O 2 (g)CO 2 + 2H 2 O(l)

NEUTRALISATION Acid + base reaction Acid + base reaction Produces salt and water. Produces salt and water. Example: Example: HCl(aq) + NaOH(aq)NaCl (aq) + H 2 O (l)

DISPLACEMENT One metal deposits on another. A metal solution reacts to become the pure solid metal. One metal deposits on another. A metal solution reacts to become the pure solid metal. Example: Example: Zn(s) + CuSO 4 (aq)ZnSO 4 (aq) + Cu(s)

Classify the following reactions: C 3 H 8 (l) + 5O 2 3CO 2 (g) + 4H 2 O(l) C 3 H 8 (l) + 5O 2 3CO 2 (g) + 4H 2 O(l)Combustion HNO 3 (aq) + LiOH(aq)LiNO 3 (aq) + H 2 O (l) HNO 3 (aq) + LiOH(aq)LiNO 3 (aq) + H 2 O (l)Neutralisation CuSO 4 + 2NaOH(aq)Na 2 SO 4 (aq) + Cu(OH) 2 (s) CuSO 4 + 2NaOH(aq)Na 2 SO 4 (aq) + Cu(OH) 2 (s)Precipitation 2Na(s) + Cu(NO 3 ) 2 2NaNO 3 (aq) + Cu(s) 2Na(s) + Cu(NO 3 ) 2 2NaNO 3 (aq) + Cu(s)Displacement KMnO 4 (s)KMnO 2 (s) + O 2 (g) KMnO 4 (s)KMnO 2 (s) + O 2 (g)Decomposition N 2 (g) + O 2 (g)2NO(g) N 2 (g) + O 2 (g)2NO(g)Combination