- Glossary
- Practice Exercises
amphoteric - able to behave as both an acid and a base.
electronegativity – the ability of an atom to attract the bonding electrons in a covalent bond.
ionization energy - the energy needed to remove 1 mole of electrons from 1 mole of atoms of an element in the gaseous state to form 1 mole of gaseous ions.
Periodic Table – the repeating patterns in the physical and chemical properties of the elements across the periods of the Periodic Table.
electron arrangement – a shorthand way of writing the number of electrons in an atom’s electron shells.
group – a column in the periodic table containing elements with the same number of outer shell electrons and similar chemical properties.
period – a row in the periodic table containing elements with the same number of full electron shells.
Property – Any characteristic of an element.
Trends down a group - the number of outer shell electrons is the same; the number of complete electron shells increases by one.
Trends across a period - the number of outer shell electrons increases by one; the number of complete electron shells stays the same.
acid – a substance that dissociates in water to produce hydrogen ions, or which donates protons and/or accepts electrons. Acids produce aqueous solutions with a pH less than 7.
alkali – a substance that dissociates in water to produce hydroxide ions, or which accepts protons and/or donates electrons. Alkalis form aqueous solutions having a pH greater than 7.
amphoteric – a substance that has the characteristics of an acid and an alkali and is capable of reactingсhemically either as an acid or an alkali. For example, aluminium oxide (Al2O3) is amphoteric: it reacts with acids to produce salts, and with alkalis to produce aluminates (substances containing the ion [Al(OH)4]-).
base – a compound that dissolves in water to produce an alkaline solution.
metal – an element, such as sodium and aluminium, formed from a regular lattice consisting of positivelycharged metal ions surrounded by a sea of delocalized electrons and held together by the attraction between them (metallic bonds). Metals are found on the left and middle of the periodic table.
metalloid – an element, such as silicon, that has properties (such as electrical conductivity) intermediate between metals and non-metals.
non-metal – an element, such as sulfur and chlorine, that typically has physical properties that are opposite to that of metals. For example, they typically have low melting and boiling points, solid non-metals are usually brittle, dull and act as electrical insulators. Chemically, nonmetal oxides tend to be acidic. Nonmetals are found on the right of the periodic table.
oxidation state – the charge a particular atom in a compound would have if the compound consisted entirely of separate ions. Also called the oxidation number. In ions, the oxidation state is the ionic charge. Elements are assumed to exist in the zerooxidation state.