Atoms of different elements combine to form compounds by the formation of new chemical bonds Describe how the transfer of electrons produces cations and anions, which forms ionic bonds Describe an ion as an atom or group of atoms with a positive or negative charge Describe the formation of sodium ions, Na1+, and chloride ions, Cl1- Metal elements combine with non metal elements to form a strong ionic bond. Elements either lose or gain e- in order to form a stable ion. Stability means a full outer shell. Elements from the LHS of the PT form +ive ions, as they give e-. Whereas elements from the RHS of the PT form –ive ions, as they take e-. Na is in Gp 1 and therefore gives 1 e- away to form a stable ion. Cl is in Gp 7 and therefore takes 1 e- from Na, in order to form a stable outer shell. What do the endings –ide and –ate in the names of compounds mean? Write the formulae of ionic compounds. Elements in groups 1, 2, 6 & 7 all form ionic bonds Name Formulas Oxides (O) CuO, Fe2O3, KO Hydroxides (OH) NaOH, KOH Halides (Gp 7 elements) NaCl, KBr, Nitrates (NO3) NaNO3, KNO3 Carbonates (CO3) NaCO3, Sulfates (SO4) NaSO4, CuSO4 Except for H and He, who only have 1 shell, with a maximum of 2 e-. Elements in Gp 1, give 1e- away to form a 1+ charge. Gp 2 give 2 e- away to form a 2+ charge. Elements in Gp 3, give 3 e- away to form a 3+ charge. Elements in Gp 5, take 3e- to form a 1- charge. Gp 2 take 2 e- to form a 2- charge. Elements in Gp 7, take 3 e- to form a 1- charge. Ide means a Halide ion (they have taken 1 e- to form a -ive charge) (Flouride, Chloride, Bromide & Iodide) Ate means either 3 or 4 oxygens attached (Sulphate (SO4) (Carbonate CO3)

What do ionic compounds look like? What are the properties of ionic compounds? Ionic compounds form a lattice structure, in a regular arrangement. The ions are held together by their +ive and –ive charges. The ionic bond is very strong 1) They have high melting and boiling points. 2) They do not conduct electricity as solids. 3) They do conduct electricity, when they are molten (liquid hot, melted) and in aqueous solution (in water) Explain the solubility rules of ionic compounds. What are precipitates? Predict whether a precipitate is formed. Soluble Insoluble Na, K, NH3, Pb, Ba & Ca NaCl, KCl, NH3Cl, all other Cl PbCl2, BaCl2, CaCl2, AgCl2 NaNO3, KNO3, NH3NO3 all other NO3 Pb(NO3)2, Ba(NO3)2, Ca(NO3)2 NaSO4, KSO4, (NH3)2SO4 all other SO4 PbSO4, BaSO4, CaSO4 NaCO3, KCO3, (NH3)2CO3, PbCO3, BaCO3, CaCO3, all other CO3 NaOH, KOH, NH3OH Pb(OH)2, Ba(OH)2, Ca(OH)2 all other OH Precipitates are all the insoluble ionic compounds (salts). In a reaction of solutions, look for the insoluble salt. Pb(NO3)2 + 2NaOH  Pb(OH)2 + 2NaNO3 AgNO3 + NaCl  AgCl + NaNO3 2NaOH + MgCl2 → 2NaCl  + Mg(OH)2 Fe(NO3)3 + 3NaOH → Fe(OH)3 + 3NaNO3

Which ions could be present if the precipitate formed with NaOH is: Describe tests to show the following ions: Describe tests to show the following precipitates: How is barium sulphate (BaSO4) used in medicine? Describe tests to show the following ions: Ion Test Na+ Flame test: Yellow K+ Flame test: Lilac Ca2+ Flame test: Red Cu2+ Flame test: Green-Blue CO32+ Add dilute acid and identifying the CO2. CO2 turns limewater milky. Ion Test SO32- Add BaCl  white precipitate of BaSO3 SO42- Add BaCl  white precipitate of BaSO4 To distinguish between sulfite (SO3) and sulphate (SO4), do a secondary test. Add HCl to both the white precipitates. barium sulfite dissolves, whereas barium sulfate does not dissolve. Ion Test Cl- Add AgNO3  AgCl white Br- Add AgNO3  AgBr cream I- Add AgNO3  IBr yellow SO2 Add HCl  turns damp chromate paper, green Ca2+ White Mg2+ Cu(II)2+ Blue Fe(II)2+ Dirty Green Fe(III)3+ Reddish Brown Al3+ White at first, then turns colourless when NaOH is added NH4+ No precipitate, but an escaping gas turns damp red litmus paper, blue. It is given as a ‘barium meal’ to X-ray patients because: a) it is opaque to X-rays b) it is safe to use as, although barium salts are toxic, its insolubility prevents it entering the blood. Name the precipitate formed when NaOH reacts with Which ions could be present if the precipitate formed with NaOH is: a) Brown  Iron 3   b) White Chloride, Calcium, Magnesium or Aluminium What would you see if NaOH solution was added to a solution of: a) Cu2+ ions  Cu(OH)2 = insoluble Blue precipitate   b) Fe2+ ions Fe(OH)2 = insoluble Green precipitate a) Al(NO3)3 Aluminium hydroxide   b) Ca(NO3)2 Calcium hydroxide

What is meant by lattice structure. Sodium chloride is soluble in water, but magnesium oxide is insoluble in water. Under what conditions will: a sodium chloride conduct electricity? b magnesium oxide conduct electricity? Suggest why magnesium oxide blocks are used to line the inside of blast furnaces, which produce molten iron. Substance X melts at 1530 °C and conducts electricity when solid. Explain why it is not an ionic compound. Substance Y melts at 373 °C. Describe a simple test you could do to see if it is an ionic compound. Melt substance Y and then connect it up to a circuit with a bulb and see if electricity pass through it to light the bulb. Magnesium oxide is an ionic compound and therefore has high melting point. a) Dissolve sodium chloride in water to make it aqueous. b) Melt magnesium oxide to make it molten. Ionic compounds only conduct electricity when either in an aqueous state or when molten. Give the formulae for: a sodium oxide NaO b magnesium chloride MgCl2 For each of the following compounds, give the symbols of the ions it contains and its formula: a potassium chloride Na+Cl- b magnesium oxide Mg2+O2- c aluminium hydroxide Al3+(OH-)3 Phosphide ions are P3−. Give the correct charges and write the correct formula for: a aluminium phosphide Al3+P3- What is meant by lattice structure. Lattice structure is the regular arrangement of ions in an ionic compound. The ions are held together by a strong ionic bond formed between the opposing charges of +ive and –ive ions.