Year 10 Exams Flashcards
What is a cation
A positively charged ion
What is an anion
A negatively charged ion
What is an ion?
An atom or group of atoms with a positive or negative charge
What is atomic number
Number of protons/electrons
What is mass number
Number of protons + neutrons
what is an isotope
different forms of the same element - same number of protons and electrons but a different number of neutrons
what is relative atomic mass
average mass of one atom of the element compared to 1/12 of the mass of one atom of carbon 12
how to work out relative atomic. mass
multiply the isotope number after the element by the abundance
divide by the sum of the abundance
how to tell what group element is in by electronic configuration
number of electrons on outer shell
e.g. 2.8.3 is in group 3
how to tell what period an element is in from electronic configuration
how many shells (digits of electronic configuration)
e.g. 2.7 is in period 2
what is a chemical change
when bonds between atoms break and the atoms change places and a new substance is formed
hard to reverse
difference between a pure substance and a mixture
pure - consists of only one element or compound
mixture - two or more different substances, not joined together
pure orange juice isn’t pure because
it has different substances mixed together so it’s not pure in a chemical sense
when line goes flat on a heating graph what happens
its changing state - energy we put in is breaking the forces of attraction between particles, allowing it to change state
during the change of state we are increasing the internal energy store but NOT changing the temperature
how do you know if a substance is pure
they have a specific melting point and boiling point
how do you know if a substance is a mixture
it will melt or boil over a range of temperatures
how can waste and ground water become potable (drinkable)
pour bad water into a distillation flask
heat it with a bunsen burner
put a thermometer in it
use a rubber tubing to connect condenser to a cold tap
water vapour passes into condenser where it cools and condenses
flows into a beaker to collect the pure water
how to separate a mixture of liquids
put mixture in a flask
put thermometer
attach a fractionating column and condenser above the flask
heat the flask
the liquids will have diff boiling points so they will evaporate at diff temperatures
they condense at the top bc it’s cooler
keep raising temp until u get all liquids
what is solidification
soluble salts precipitate as lumps and then settle at the bottom
it removes ions and salts from the water
what is filtration
water goes through the sand and gravel to get rid of even smaller bits
it removes smaller solids
what is chlorination
adding chlorine to the water to get rid of bacteria
removes bacteria
acronym for the stages of filtration
sorry - solidification
forgot - filtration
can’t - chlorination
covalent bond RULES
write down how many electrons in outer shell
write down how many electrons each atoms need to make a full outer shell
this is how many bonds will form
draw the structural diagram of the molecule
draw dot and cross diagram (only use outer shells)
put the atom with the highest number of bonds in the middle
draw dots and crosses for electrons
diamond vs graphite
diamond: poor conductor of electricity graphite: good conductor of electricity
diamond and graphite: high melting
why is graphite used for pencils
it’s soft so the carbon atoms form layers which are able to slide over each other
layers of hexagonal sheets - easy to break
how many covalent bonds does diamond have
four
why is graphite a good conductor of electricity
it has 3 covalent bonds meaning it has a spare, delocalised electron to carry around charge
what do ionic compounds have
regular lattice arrangement
strong electrostatic forces of attraction between oppositely charged ions
ionic compound properties
high melting boiling point
can’t conduct electricity due to ions held in place (except graphite)
when they melt, electrons are free to flow and carry charge
some dissolve in water so the ions separate and are free to move around
limitations of structural models
2D representations don’t show shape of substances or size of atoms
dot and cross diagrams don’t show anything about size or how ions or atoms are arranged
3D models only show outer layer of the substance but are good at showing arrangement of ions
what’s a covalent bond
strong bond that forms when a pair of electrons are shared between two atoms
simple molecular substance properties
weak forces of attraction between molecules
weak intermolecular forces
gases or liquids at room temp
don’t conduct electricity - has no charge or no free electrons
