YEAR 10 SCIENCE

1. YEAR 10 SCIENCE CHEMISTRY

2. Matter Matter = any material substance with Mass & Volume

3. Solid Gas Liquid Matter comes in 3 phases

4. Solid Definite Shape Definite Volume

5. Liquid Indefinite Shape – takes the shape of the container Definite Volume

6. Gas Indefinite Shape – takes the shape of the container Indefinite Volume – can expand and be compressed

7. Atom the smallest particle making up elements

8. Sub-atomic Particles Protons p+ - positive charge, in nucleus Neutrons n0 – no charge, in nucleus Electrons - e- negative charge, orbiting nucleus

9. 6 Atomic # C 12.011 Atomic Mass Drawing an Atom of Carbon = # of p+ and # of e- Carbon has 6 p+ and 6 e- minus Atomic # = # of n0 Carbon has 6 n0

10. e- e- 6 p+ 6 n0 e- e- e- e- Drawing an Atom of Carbon

11. 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.

12. PERIODIC TABLE

13. H = Hydrogen Na = Sodium Ca = Calcium C = Carbon K = Potassium O = Oxygen I = Iodine N = Nitrogen Cl = Chlorine S = Sulfur P = Phosphorus Examples of Elements

14. Nucleus Example • Chlorine, atomic number 17. 2 electrons fit in the first shell and then it is full. There are 7 electrons left so they go in the outer shell 8 electrons fit in the second shell and then it is full.

15. 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.

16. Nucleus An abbreviation • Chlorine, atomic number 17. The arrangement of electrons can be shortened to: 2, 8, 7

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

18. 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

19. 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)

20. 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

21. 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

22. 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

23. H + O H2O = O H H Compounds Compounds – are made of 2 or more different atoms combined to form Molecules Chemical formula lists the number of different atoms in a single molecule Structural formula shows the arrangement of the atoms in a single molecule

24. H H C C O C6H12O6 H H H C C H O H O H O H O H C C Chemical formula H O H Structural formula Molecules Glucose Sugar

25. Inorganic Compounds Organic Compounds or 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

26. H + O = H2O = Water H + Cl = HCl = Hydrochloric Acid C + O = CO2 = Carbon Dioxide Na + Cl = NaCl = Common Table Salt Examples of Inorganic Compounds

27. Carbohydrates = Sugars, starches & cellulose C, H + O C, H + O Lipids = Fats & Oils C, H, O, N, & sometimes P + S Proteins C, H, O, N, + P Nucleic Acids – DNA & RNA Examples of Organic Compounds

28. IONS We already know: • Atoms are neutral - no charge • Electrons are on the outside of atoms • Atoms react by exchanging or sharing electrons • When atoms exchange electrons, ions are formed.

29. 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.

30. Have the following ions gained or lost electrons?

31. 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)

32. How can you tell? Method 1: The periodic table

33. 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. • 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.

34. Example:

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

37. Temperature changes • Endothermic reactions- absorb heat and as a result the temperature falls. • Exothermic reactions- release heat and as a result the temperature rises.

38. YEAR 10 CHEMISTRY REACTION TYPES

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

40. COMBINATION • Joining reaction • Two or more substances combine to form a new substance. • X + Y XY • Example: C (s)+ O2(g) CO2(g)

41. DECOMPOSITION • Break down reactions • Opposite of combination reactions. • XY X + Y • Example: 2NaN3 (s) 2Na(s) + 3N2(g)

42. PRECIPITATION • Two solutions mixed together make a solid. • Example; AgNO3(aq) + NaCl(aq) AgCl (s) + NaNO3(aq)

43. COMBUSTION • Uses oxygen, happens quickly and produces heat and light. • Example: CH4 (g) + 2O2(g) CO2 + 2H2O(l)

44. NEUTRALISATION • Acid + base reaction • Produces salt and water. • Example: HCl(aq) + NaOH(aq) NaCl (aq) + H2O (l)

45. DISPLACEMENT • One metal deposits on another. A metal solution reacts to become the pure solid metal. • Example: Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s)

46. 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