SCH 3U1 – Elements and the Periodic Table

Term Comments

Element • are pure substances that cannot be broken down into simpler substances by chemical means.• Composed of one kind of atom.

Compound • a pure substance that can be broken down by chemical means to produce two or more pure substances.• they contain two or more elements combined in a fixed proportion.

Metal • an element that is a conductor of electricity, malleable, ductile and lustrous. Most elements are metals.

SATP • standard ambient temperature and pressure.• 100 kPa, 25˚C.• common lab conditions.

STP • standard temperature and pressure• 101.3 kPa, 0˚C• used as a standard to compare substances to one another.

Term Comments

Non – metals • do not conduct electricity in solid form and are brittle.• mostly gases and solids (bromine – liquid)

Metalloids • are elements located near the staircase line in the periodic table.• have properties of metals and non-metals.

IUPAC • international union of pure and applied chemistry.• organization compiling and approving chemical names, symbols and units.

s, l, g • symbols used to represent the state of an element (solid, liquid, gas)

Triad • a group of three elements with similar properties. (Li, K, Na)

Periodic Law (Mendeleev)

• States that elements arranged in order of increasing atomic mass show a periodic recurrence of properties at regular intervals.

Periodic Trends • a pattern or trend of gradual change in properties within a period or group in the periodic table (PT).

Term Comments

Group • A column of elements in the periodic table referred to as a family.• they share similar chemical properties.

Period • a row in the periodic table.• properties change from metallic elements on the left to non-metallic elements on the right.

Alkali metals • an element in group 1.• extremely reactive, more reactive as you move down the column.

Alkaline earth metals • an element in group 2.• highly reactive but less so than group 1.• reactivity increases as you move down the group.

Halogens • an element in group 17.• extremely reactive.• less reactive as you move down the group.

Term Comments

Noble gases • an element in group 18.• unreactive gases.• also called inert gases.

Representative elements

• an element in any of groups 1, 2 and groups 13 – 18. They most closely follow the periodic law.

Transition Metal • elements in groups 3 through 12

Lanthanides (rare earths)

• lanthanum and the 13 elements that follow it in the 6th row of the P.T. (elements 57 – 70)

Actinides • actinium and the 13 elements that follow in the 7th row of the PT. (elements 89 – 102)

Transuranic elements

• elements that follow uranium in the PT (elements 93 onward) they are not naturally occurring (synthetic).