atoms, metals and acid/base reactions Aspects of Chemistry atoms, metals and acid/base reactions

Atomic structure review the particle nature of matter identify and diagram the parts of an atom electron shells The periodic table: Groups and Periods Be is in Group 2, Period 2; what does this mean in terms of its atomic structure? Click here for a very good overview of this topic and here for a quiz Answer: Be has 2 outer shell electrons AND 2 shells

Ions An ion is formed when an atom donates OR accepts an electron (s). Follow this link for a very good overview. A positive ion is formed when an atom donates electrons A negative ion is formed when an atom accepts electrons What is the formula of calcium ion? Explain your answer Answer: Ca2+. When Ca atom donates 2 electrons, it’s left with 18 electrons and 20 protons. There is a ‘surplus’ of 2 (+) protons

Writing formulae of ionic compounds Step 1: write the formulae of the ions Step 2: work out the minimum number of each ion that is needed to make a finished formula that has a total charge of zero Step 3: write the finished formula with the positive ion first; don’t show the ion charges. If the ion is a compound ion, then enclose it in brackets if more than one is present in the finished formula Follow this link for a very good overview and quiz

Ionic formulae: worked examples Example 1: write the formula of the compound formed from the following ions: Iron (III) ion and oxide Step 1: The ion formulae are Fe3+ and O2- Step 2: A minimum of 2 x Fe3+ and 3 x O2- are needed to give a total charge of zero (2 x 3+ = 6+ and 3 x 2- = 6-; 6+ added to 6- = 0) Step 3: The finished formula (for iron (III) oxide) is Fe2O3 Example 2: what is the formula for the compound produced from the following ions: carbonate and zinc ion The ion formulae are CO32- and Zn2+ The minimum number needed of each is one (2- + 2+ = 0) The finished formula (for zinc carbonate) is ZnCO3 Write the formulae for: barium hydroxide, magnesium nitrate and aluminium chloride Ba (OH)2 , Mg (NO3)2 and Al Cl3

Metals Identify the periods and the groups in which the metals are found Follow this link to find out about the arrangement of metal atoms Describe the key properties of metals Click here to view the effect of heating on metals Describe the reaction of metals with oxygen, water and dilute acid Reactivity series What causes rusting?

Metal reactions Write a word equation for the reaction of magnesium with oxygen What test could you perform to find out if metal oxides are acidic or basic? Write a word and balanced symbol equation for the reaction of calcium with water What gas is produced when metals react with acid? Magnesium + oxygen magnesium oxide Add universal indicator; if it turns blue or purple, they’re basic calcium + water calcium hydroxide + hydrogen gas Ca + 2H2O Ca(OH)2 + H2 hydrogen

Uses of metals Relate their uses to their properties and reactivity: Copper: plumbing (malleable; not very reactive); sculpture (malleable, shiny); electrical wiring (ductile, very high electrical conductivity); cooking utensils (high heat conductivity) Aluminium: structural uses (malleable, low density, very reactive, but aluminium oxide coating limits further corrosion); electrical wiring (ductile, high conductivity); cooking utensils (malleable, heat conductivity) Iron: structural (strong); frying pans (heat conductivity and malleable); alloyed to make steel (multiple applications) Lead: ridges in roofing (malleable, low reactivity); fishing sinkers and bullets (dense, malleable)

Metal compounds Metal oxides Metal hydroxides Metal carbonates Metal hydrogen carbonates All the above are bases

Acids and Bases pH less than 7 Turn litmus red Turn universal indicator yellow, orange or red Neutralise bases (metal oxides and hydroxides) React with carbonates and hydrogen carbonates to produce CO2 Acids pH greater than 7 Turn litmus blue Turn universal indicator blue or purple Neutralise acids Bases