elements, compounds, mixtures and basic chemistry Flashcards
define element
the same type of atom, that cannot be chemically broken down
define mixture
two or more substances, not chemically combined but mixed together
what is an atom?
the smallest unit, of an element.
define compound
two or more TYPES of atoms that are chemically bonded together. All compounds are molecules, but not all molecules are compounds (i.e H2)
what’s a molecule?
a group of atoms that are covalently bonded together.
Metal properties
- metallic bonding
- malleable (can be hammered or pressured INTO shape without breaking or cracking)
- good heat conductors
- high melting and boiling points
- shiny
- Sonorous (makes a ringing sound when we strike them)
- Ductile (change shape/be deformed without losing strength)
- Higher density
- Usually solid at room temperature
Non-metal properties
- Dull in colour
- Brittle
- Low melting and boiling points
- Lower density
- Poor heat conductors
- Not sonorous
- Not ductile
- may be either solid, liquid or gas at room temperature
Transition metal properties
Include all typical metal properties +
- can form more than one ion
- are very good catalysts (substances hat increase the rate of chemical reactions, without being used up themselves)
Alkali metal properties
Are more reactive the further down you go, as it is easier to lose the valance electrons due to the larger distance between the electron and the nucleus (+ only having to lose 1 e-)
- The density of all alkali metals increases as you go further DOWN the group
- The melting and boiling points of alkali metals DECREASES as you go down the group
They are the most reactive with –> WATER, CHLORINE and OXYGEN
Alkali metal + water –> ?
Alkali metal + H2O –(reacts vigorously)—> metal hydroxide + hydrogen gas
2NA + 2H2O –> 2NAOH + H2 (balanced)
Alkali metal + oxygen –> ? (word eq)
Alkali metal + O2 —> metal oxide
the type of oxide depends on the metal.
(i.e sodium oxide and sodium peroxide)
What happens when sodium and chlorine react?
a salt (sodium chloride) is formed and lot’s of heat is released during the reaction
Diatomic molecules
exist in pairs (H2/N2/O2/F2?Cl2/I2/Br2)
Phosphorous and sulphur are NOT diatomic molecules but they do come in pairs.
List all the polyatomic ions and their charges
Carbonate = CO3 (2-)
Hydroxide = OH (-)
Nitrate = NO3 (-)
Sulphate = SO4 (2-)
Ammonium = NH4 (+)
Phosphate = PO4 (3-)
polyatomic ions are…
A group of atoms that have a charge
