SCH 3U1 – Elements and the Periodic Table TermComments 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 kPa, 0˚C used as a standard to compare substances to one another.

TermComments 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).

TermComments 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.

TermComments 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 6 th row of the P.T. (elements 57 – 70) Actinides actinium and the 13 elements that follow in the 7 th 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).