Chemistry C4

Atom - the smallest part an element can be divided into using a chemical reaction

Element - contains atoms which are all identical

Molecule - two or more atoms, chemically bonded. The atoms may be the same or different

Compound - made up of two or more different elements chemically bonded together

columns = groups

rows = periods

Group 1 - alkali metals Group 7 - halogens

Group 2 - alkali earth metals Group 0 - noble gases

Relative mass and charge

Protons - charge = +1, mass = 1

Neutrons - charge = 0, mass = 1

Electrons - charge = -1, mass = 0.0005

Shell rules

1st shell - 2 electrons 3rd shell - 8 electrons

2nd shell - 8 electrons 4th shell - as many as you like

Neutrons = mass number - atomic number

Order

1. Number on first
2. Number on second
3. Number on third

• strong
• solid at room temperature
• hard
• malleable
• shiny
• good conductor of heat and electricity
• high density
• high melting point
• ductile
• sonorous

• only three triads
• didn't include all of the elements

Alkali metals and water

metal + water -> hydrogen + metal hydroxide

Alkali metals and chlorine

metal + chlorine -> metal chloride

Alkali metals and oxygen

metal + oxygen -> metal oxide

• As you go down the group, the melting/boiling points increase
• The halogens are volatile (they turn into a gas very easily)

• Solid - (s)
• Liquid - (l)
• Gas - (g)
• Aqueous solution - (aq) - dissolved in water

Ionic bonds - between metals and non-metals

Properties

• made of crystals
• often soluble in water
• high melting points
• conduct electricity when molten or dissolved but not when solid

Salt - Na+Cl-

Properties

• usually soluble in water
• conducts electricity whne dissolved and molten (ions are free to move)
• does not conduct electricity when solid (ions are fixed)
• high melting/boiling points (strong attractions)
• crystalline appearance (lattice arrangement)

Lithium - bright red

Potassium - light pink/lilac

Sodium - orange (bright)

Calcium - red/orange

Barium - green/yellow

Copper - green/blue

Group 1 -> +1  Group 2 -> +2 Group 3 -> +3

Group 4 -> N/A Group 5 -> -3 Group 6 -> -2

Group 7 -> -1 Group 0 -> N/A