3.1.3 - pure substance Flashcards
what do pure substances contain?
only ONE type of particles
pure substance melting+ boiling point?
have a single sharp melting and boiling point
what do mixtures contain?
different types of particle
mixtures melting + boiling point?
melt and boil over a range of temperatures
what is an element?
a substance containing only one kind of atom
what is a compound?
a substance containing different types of atoms which are chemically bonded together
chemical test for water?
anhydrous copper(II) sulphate
turns white -> blue
physical tests for water?
melting point = 0 degrees
boiling point = 100 degrees
pure water would melt/boil exactly on this temp
properties of metals:
- high MP/BP
- electrical conductors
- malleable
- shiny
- form alkaline oxides
properties of non-metals:
- low MP/BP
- electrical insulators
- brittle
- dull
- form acidic oxides
what is element combustion?
when an element reacts with oxygen to produce an oxide
element combustion equation?
element + oxygen -> element oxide
combustion of magnesium equation?
magnesium + oxygen -> magnesium oxide
2Mg + O2 -> 2MgO
observations of combustion of magnesium?
bright white light
white powder formed
combustion of sulphur equation?
sulphur + oxygen -> sulphur dioxide
S + O2 -> SO2
observations of combustion of sulphur?
blue flame
combustion of hydrogen equation?
hydrogen + oxygen -> water
2H2 + O2 -> 2H2O
observations of combustion of hydrogen?
squeaky pop
when metal oxides dissolve in water do they form an acidic or alkaline solution?
alkaline
when non-metal dioxides dissolve in water do they form an acidic or alkaline solution?
acidic
what bonding happens between metals?
metallic bonding
what bonding happens between non-metals?
covalent bonding
what bonding happens between metals and non-metals?
ionic bonding
what does the name and state of the oxide formed in element combustion depend on
whether the element was a metal or non-metal
metal -> metal oxide (solid)
non-metal -> non-metal oxide (gas)
what can you do to determine whether an unknown element is metal or non-metal
- combust it in oxygen
- dissolve the oxide formed
- check the pH of the solution with an indicator
what is a compound
a substance containing more than one type of atom, chemically bonded together
how can compounds often be formed
heating their elements together
eg. if you heat zinc and sulphur you make zinc sulphide
what are the three types of compounds
metallic
ionic
covalent
which compound bonds non-metals
covalent
which compound bonds metals and non-metals
ionic
which compound bonds metals
metallic
