Atomic Structure- Elements, Compounds & Mixtures Flashcards
An element is a substance which contains only one ____ of atom.
An element is a substance which contains only one TYPE of atom.
A ________ is a substance which contains two or more types of elements ______ together.
A compound is a substance which contains two or more types of elements bonded together.
Mixtures contain _________ elements or compounds that can be __________ as they are
not __________ ______ together.
Mixtures contain different elements or compounds that can be separated as they are
not chemically bonded together.
In chemical reactions the starting materials are called _________ and new ________ are made.
In chemical reactions the starting materials are called reactants and new products are made.
What are the four different states and their symbols?
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous (dissolved in solution)
You separate an insoluble solid from a solution by _________ it out. The solid can then be
washed and dried to remove any ___________.
You separate an insoluble solid from a solution by filtering it out. The solid can then be
washed and dried to remove any impurities.
To separate a _______ salt from a solution you evaporate the water to produce _________ of salt.
To separate a soluble salt from a solution you evaporate the water to produce crystals of salt.
To separate and collect a liquid from a mixture you use _____________. You can use distillation to separate a _______ of liquids.
To separate and collect a liquid from a mixture you use distillation. You can use distillation to separate a mixture of liquids.
what are some physical separating techniques that would be used to separate a mixture
filtration, distillation, crystallization and chromatography
what is a molecule
a substance that has any elements chemically combined, even if they are the same element
Each element on the periodic table has a symbol. what dope this symbol always start with
a capital letter
what does a chemical formula tell us
the elements in a molecule and the numbers of atoms of each element
true or false?
the numbers of atoms of each element is fixed
true
we can’t change the numbers, because if we did we would end up with a different compound
what happens if you have brackets within a chemical formula
the number on the outside of the bracket multiplies everything within the bracket
what do state symbols tell us
the physical state of a chemical e.g. solid, liquid, gas or dissolved in water
what equipment is used during filtration
filter funnel, filter paper, conical flask
how does the water pass through the filter paper
through tiny holes called pores
once the liquid passes through the filter paper what is it called
the filtrate
how can you make crystallisation happen quickly
by gently heating our solution to evaporate the water quicker then leaving it to evaporate
why is it sometimes better to leave the solution to evaporate by itself
certain chemicals will break down if you heat them
what are the two stages involved in simple distillation
- evaporate the liquid by heating it which turns it into a vapour
- next you condense the vapor back into a liquid by cooling
in simple distillation where do you place the liquid
into the flask
what is the flask connected to
a continuous glass tube
what surrounds the glass tube
a condenser
how does a condenser work
cold water from the tap continuously runs through the condenser to keep the internal glass tube cold
expelling how simple distillation works
- heat the solution by using a bunsen Bruner to turn the liquid into a vapor
- the vapor rises up the glass tube
- the thermometer reading then increases
- the vapor passes into the condenser and is condensed back into a liquid
- we then collect the liquid into a beaker
- we are then left with crystals of our solid in the flask and liquid in the beaker
how long do you heat the liquid
until it boils
how is fractional distillation different from simple distillation
we separate a mixture of different liquids
factional distillation only works if the liquids have _________ _______ points.
factional distillation only works if the liquids have different boiling points
the equipment for simple distillation is the same as distillation apart from one thing. what is difference
the flask that contains the mixture is attached to a long column containing hundreds of glass beads - a fractionating column
explain how fractional distillation works
- gently heat the mixture to allow both our liquids to start to evaporate - the one with the lower boiling point will evaporate quicker
- the vapors reach the fractionating column and condense back into a liquid into the conical flask
- the liquids continue to evaporate and condense which increases the amount of the lower boiling point chemical in the fractionating column.
- the warm vapors pass up the column and reach the thermometer
- the vapors then enter the condensor which cools them down and turns them back into the liquid - this liquid is still a mixture of two chemicals
- once the thermometer stops rising it will have reached the lowest boiling point meaning now we mainly only have 1 chemical
- as this chemical condense we collect it in a new beaker
- the liquid will continue evaporating and condensing and once the thermometer is a new constant temperature the other liquid is ready to be collected
what is paper chromatography
a physical separation method which allows us to separate different substances based on their solubilities
explain how you would carry out paper chromatography when looking at what is in different colored pens
- take a piece of chromatography paper
- draw a line near the bottom in pencil
- put a dot of your first color on the pencil line, and next to it put your second color - you can do this for several colors as long as there is room on the paper
- place the bottom of your paper into a solvent
- The solvent makes its way up the paper and dissolves the ink in the two colored dots - meaning the ink is carried up the paper
what is the paper called and why
the stationary phase - because it doesnt move
what is the solvent called and why
the mobile phase - because it moves
how can you tell if a color is pure
if there is only 1 spot
how can you tell if a color is a mixture of colors
the single dot will separate into two or multiple dots
why does paper chromatography work
because different substances have different solubilities
true or false?
a less soluble substance travels further up the paper
false
a more soluble substance travels further up the paper
why is the starting line drawn in pencil
do that the solvent doesnt carry the pen ink up with it
