Elements, mixtures and compounds Flashcards
What is an element?
an element is a pure substance that cannot be broken down into a simpler substance. An element is made out of one type of atom only
What state are elements?
They can be solids, liquids or gases
What is a compound?
Most substances are not elements because they are not made up from one type of atom only. A compound is made from atoms of at least two different elements joined together by a chemical bond.
What is a mixture?
these are different substances mixed together but not joined by chemical bonds; there is no link between them. The parts of a mixture can be elements or compounds or both, it makes little difference and the mixture can have any composition.
What is a chemical formula?
a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule
What is the composition of a compound?
it has a fixed composition that can’t change
Does mixing substances change their properties?
No
What is the appearance of iron?
silver/grey solid
What is the appearance of sulphur?
yellow solid
What is iron’s density compared to water?
it’s more dense (it sinks in water)
What is sulphur’s density compared to water?
sulphur powder floats
What is the effect of a magnet on iron?
iron is attracted to a magnet as it is magnetic
What is the effect of a magnet on sulphur?
it has no effect as sulphur is not magnetic
What is the effect of dilute hydrochloric acid on iron?
it reacts with iron and gives off hydrogen
What is the effect of dilute hydrochloric acid on sulphur?
it doesn’t react with sulphur
What colour is the mixture of iron and sulphur?
grey/yellow
What happens if you move a magnet underneath the paper that has the iron/sulphur mixture on it?
the iron will follow the magnet as it moves, but the sulphur does not
Is it easy to separate the iron/sulphur mixture?
yes, by using a magnet
What happens if the iron/sulphur mixture is added to a half-filled beaker of water?
the iron sinks and the sulphur powder floats
What would happen if large lumps of sulphur were used instead of sulphur powder in water?
they would sink
Some of the iron/sulphur mixture is added to hydrochloric acid. What will happen?
The iron will react with the hydrochloric acid producing hydrogen gas and the sulfur doesn’t (it floats)
Is hydrogen an element?
yes
What are the properties that all metals have?
-good conducters of electricity
-good conducters of heat
-malleable
-ductile
-shiny
What is iron (ll) sulphide?
It’s a compound made by combining iron and sulphur that has its own set of properties
Is it easy or difficult to separate the elements in a compound?
it’s difficult
What is the appearance of iron (ll) sulphide?
Black solid
What is of iron (ll) sulphide’s density compared to water?
it’s more dense
What is the effect of a magnet on iron (ll) sulphide?
it has no effect
What is the effect of dilute hydrochloric acid on iron (ll) sulphide?
it gives off a gas that smells like rotten eggs
What is the gas made when iron (ll) sulphide is heated with dilute hudrochloric acid?
hydrogen sulphide
Is hydrogen sulphide an element, compound or mixture?
it’s a compound
What colour is hydrogen sulphide?
colourless
What are the two elements combined to form hydrogen sulphide?
Hydrogen and sulphur
Does hydrogen sulphide have the same properties as hydrogen and sulphur?
no
What is the word equation for iron and sulphur?
iron + sulphur → iron (ll) sulphide
Does iron (ll) sulphide have the same properties as an iron/sulphur mixture?
no
What type of reaction took place between iron and sulphur?
synthesis, as two elements are combined to give a singe product
What is the name of a reaction that gives off heat?
exothermic
