C3 Opener – Development of the periodic table C3: What I should already know LINKS with C1 & C2

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd DECOMPOSE Heat or electricity makes most substances DECOMPOSE – break down into others. limestone carbon dioxide lime calcium oxygen hydrogen water carbon EXAMPLES C1 Section 1

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd ELEMENTS A few substances cannot be decomposed by ordinary laboratory processes. They are called ELEMENTS. 92 elements make up all known substances. Only these ten elements were known before iron copper silver sulfur carbon tin lead antimony bismuth arsenic C2 Section 1

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd COMPOUNDS Elements can join together to make compounds. The properties of a compound are quite different from those of its constituent elements. oxygen + hydrogen water (hydrogen oxide) react together to make a compound elements C2 Section 1 & 2

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd PARTICLES We can understand how solids, liquids and gases behave by understanding how their particles move. In liquids, the particles can move around but stay in close contact. In solids, the particles vibrate but are in fixed positions. In gases, the particles are free to spread out to an unlimited extent. container C2 Section 1 & 2

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd MODELS HEALTH WARNING! Atoms and molecules are too small to see. They are rarely round and never coloured. Using diagrams, balls and sticks, and computer animation helps us to understand what is happening. Matter behaves like the model in some ways – but not in all ways.

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd ATOMS The smallest particles that take part in chemical reactions are called atoms. Atoms of the same element have the same proton number. H He Li B Be C N F Ne Na Mg S Cl Ar K Ca Each chemical symbol stands for one atom of the element. O Al Si P Elements 1–20 C2 Section 1 & 2

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd The size of the nucleus compared with the size of the atom is like ‘the size of a man’s fist compared with the dome of St Paul’s Cathedral’ (Rutherford). INSIDE AN ATOM The nucleus contains almost the entire mass of the atom. Tiny electrons whizz around the nucleus. Most of the atom is empty space. OUT OF SCALE DIAGRAM. Diameter of atom should be MUCH larger C2 Section 1

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd INSIDE A NUCLEUS sodium nucleus 11 protons, each +1 charge. 12 neutrons, each 0 charge. protons and neutrons have the same mass Na mass number = protons + neutrons proton number = total nuclear charge Number of electrons that orbit the nucleus = number of protons + C2 Section 1

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd THE MODERN PERIODIC TABLE Rows are called periods Columns are called groups When the elements are arranged in order of proton number, the elements in each group show family resemblances C2 Section 1

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd argon, Ar BONDING Atoms can join together in groups to make molecules. Molecules of some gaseous elements Molecules of some simple compounds oxygen, O 2 hydrogen, H 2 nitrogen, N 2 water, H 2 O ammonia, NH 3 Huge numbers of atoms, molecules or ions can join together in regular patterns, making crystals such as diamond, ice or salt. These are called giant structures. carbon dioxide, CO 2 C2 Section 2

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd ACIDS more acidic more alkaline pH 7pH 14 pH 1 neutral pH scale acid + base  salt + water Acids have a sour taste and change the colour of indicators. wasp stings are acidic bee stings are alkaline indigestion tablets contain an alkali vinegar is a weak acid an alkali is a soluble base acid + carbonate  carbon dioxide C2 Section 7

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd ACIDS + METALS more reactive less reactive Au Ag Cu Sn Fe Zn Mg Ca Li Na K react with cold water do not react with dilute acid react with dilute acid Test for hydrogen with a lighted splint. acid + metal  hydrogen + salt 2HCl(aq) + Zn(s)  H 2 (g) + ZnCl 2 (aq) water + metal  hydrogen + metal hydroxide 2H 2 O(l) + Ca(s)  H 2 (g) + Ca(OH) 2 (aq) C2 Section 7

C3 Opener – Development of the periodic table C3: What I should already know AQA Science © Nelson Thornes Ltd FORMULAE H 2 SO 4 Molecule Mass of 1 mole (2  1) (4  16) = 98 g BaCl 2 Giant structure with twice as many Cl – ions as Ba 2+ ions Mass of 1 mole (2  35.5) = 208 g Cu Giant structure of atoms Mass of 1 mole = 63.5 g Some examples C 6 H 12 O 6 Molecule Mass of 1 mole = (6  12) + (12  1) + (6  16) = 180 g H2OH2O molecule Mass of 1 mole (2  1) + 16 = 18 g C Giant structure of atoms Mass of 1 mole = 12 g Al 2 O 3 Giant structure with Al 3+ and O 2 – ions in a 2:3 ratio Mass of 1 mole (2  27) + (3  16) = 102 g C2 Section 3