Coaching Centre
The periodic table review
A summary of the whole Periodic Table chapter, key words, and a mixed test covering the history and layout of the table, metals and non-metals, group trends, ions, ionic and covalent bonding, and conductivity.
Use this page to check the whole chapter. Read the summary, make sure you can explain every key word, then do the test without looking back.
Chapter summary
| Topic | What you need to know |
|---|---|
| 2A History | Lavoisier's list (1789); Döbereiner's triads; Newlands' octaves; Mendeleev (1869) ordered by atomic weight and properties, left gaps and predicted gallium, scandium and germanium; noble gases added 1894–98; Moseley (1913): order by atomic number; McMillan and Abelson made neptunium (1940), Seaborg plutonium and the actinoid row; elements 113–118 named in 2016. |
| 2B Navigating | Ordered by atomic number. Groups (columns 1–18): same number of outer electrons, similar properties. Periods (rows 1–7): same number of shells. Metals left and centre, non-metals right, metalloids on the staircase. Lanthanoids and actinoids pulled out below. |
| 2C Metals and non-metals | Metals: shiny, malleable, ductile, conduct, mostly high melting points. Non-metals: dull, brittle, insulators, low melting points. Metalloids are semiconductors. Alkali metals react with water (hydroxide + hydrogen), more reactive down the group. Transition metals: hard, coloured compounds, catalysts. Halogens: coloured, less reactive down the group. Noble gases: unreactive, full shells. |
| 2D Ions | Atoms react to get a full outer shell. Metals lose electrons → cations; non-metals gain → anions. Charges: group 1 1+, 2 2+, 13 3+, 15 3−, 16 2−, 17 1−. Non-metal ions end in -ide. Group 1 reactivity rises down the group (outer electron further away); group 17 falls down the group. |
| 2E Ionic compounds | Metal + non-metal; ionic bond = attraction between opposite ions; crystal lattice; high melting point, hard, brittle; conduct only molten or dissolved. Formula = simplest ratio with zero total charge. Polyatomic ions in brackets when more than one. |
| 2F Covalent molecules | Non-metals share electron pairs. Single, double (O₂, CO₂), triple (N₂) bonds. Dot-and-cross and structural diagrams. Weak forces between molecules → low melting points, no conduction. Covalent networks (diamond, graphite, silica) have very high melting points. Prefixes mono-, di-, tri- for molecular names. |
| 2G Electricity | Conduction needs mobile charged particles. Metals: sea of delocalised electrons, also explains malleability and lustre. Alloys are harder. Ionic: conduct only molten or in solution (electrolysis). Covalent molecular: never conduct. Graphite conducts. |
Putting it together
The whole chapter runs on one idea: an element's outer electrons decide how it behaves, and its position in the table tells you how many outer electrons it has. Group number gives the outer electrons; outer electrons decide whether an atom loses, gains or shares electrons; that decides whether it forms ionic, covalent or metallic bonds; and the bonding decides the properties you can see and measure, such as melting point, hardness and whether it conducts. Mendeleev found the pattern in the properties without knowing any of this. Fifty years later, the discovery of electrons and the nucleus explained why his table works.
Key words
alkali metal · alkaline earth metal · alloy · anion · atomic number · cation · covalent bond · covalent network · crystal lattice · delocalised electrons · diatomic · dot-and-cross diagram · double bond · ductile · electrolysis · group · halogen · ion · ionic bond · ionic compound · lone pair · lustrous · malleable · metallic bond · metalloid · molecule · noble gas · period · polyatomic ion · reactivity · semiconductor · structural formula · transition metal · triple bond · valence electron
Test yourself
Mendeleev's table was convincing mainly because
Gallium, scandium and germanium matched his predictions.
An element in period 2, group 16 is
Two shells, six outer electrons: 2,6 is oxygen.
Which element is most reactive?
Group 1 reactivity increases down the group; rubidium is lowest here.
The formula of calcium nitride (Ca²⁺ and N³⁻) is
3 × (+2) = +6 and 2 × (−3) = −6.
Hydrogen chloride, HCl, is formed by
Both are non-metals, so they share electrons in a covalent bond.
Copper wire conducts electricity because it contains
Metals have a sea of free electrons.
Which substance has the lowest melting point?
Oxygen is a covalent molecular substance with weak forces between its molecules.
Name each region of the periodic table.
What type of bonding does each substance have?
Order these from the fewest to the most outer electrons.
The modern periodic table is arranged in order of atomic . Elements in the same have similar chemical properties. Metals lose electrons to form ions. Non-metals bond with each other by electrons. Ionic compounds conduct electricity when molten or .
Potassium (group 1) and bromine (group 17) react to form potassium bromide. Describe how the bond forms, write the formula, and predict two properties of potassium bromide, explaining each.
Potassium has one outer electron, which it loses to become K⁺ with a full outer shell. Bromine has seven outer electrons and gains the electron from potassium to become Br⁻, also with a full outer shell. The oppositely charged ions attract each other strongly; this is an ionic bond, and huge numbers of ions build up a crystal lattice. The charges balance 1:1, so the formula is KBr. Potassium bromide will have a high melting point, because a lot of energy is needed to overcome the strong attractions between ions throughout the lattice. It will conduct electricity when molten or dissolved in water but not as a solid, because only then are the ions free to move and carry charge.