Elements, Compounds and mixtures

Elements

pure substances that cannot be broken down into other simpler substances by physical or chemical means.

Group 1 elements (alkali metals)

lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr)

Group 2 elements (alkaline earth metals)

beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra)

Group 14 elements

• a non-metal [carbon(C)]

• metalloids or semi-metals [silicon (Si) and germanium (Ge)]

•metals [tin (Sn), lead (Pb) and flerovium (Fl)

Group 17 elements

halogens [fluorine (F), chlorine (CI), bromine (Br), iodine (l), astatine (At) and tennessine (Ts)]

Group 18 elements

noble gases [helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) an oganesson (Og)]

• Properties of Metals

•Shiny

• High density

• Ductile (can be drawn into wire)

• Malleable (can be hammered into thin. sheets without cracking)

• Sonorous (rings when struck)

• High melting and boiling points

• Good conductors of heat

• Good conductors of electricity

Properties of Non-Metals

• Dull

• Low density

• Non-ductile

• Non-malleable

• Non-soronous

• Low melting and boiling points

• Poor conductors of heat or thermal insulators

• Poor conductors of electricity or electrical insulators

Metalloids or semi-metals

considered unique in the sense that they possess some properties of metals and some properties of non-metals.

Properties of Metalloids

• solid

• some shiny and some dull

• brittle/ non-malleable

• Non-ductile

• Non-tensile

• Melting and boiling point varies

• some conduct heat

• some conduct electricity

Compounds

pure substances that are formed when two or more elements combine chemically in a chemical reaction.

And is made up of different elements combined in a fixed ratio.

Properties of Compound

• A compound is formed by chemical reactions.

• A compound can only be broken down into its constituent elements by chemical reactions.

• The properties of a compound and constituent elements are different.

• The elements in a compound combine in a fixed proportion by mass.