C1 Atomic Structure Flashcards
What is everything made of? a_____
atoms
What is a compound?
Compounds are substances formed from 2 or more elements, the atoms of each are in fixed proportions throughout the compound and they’re held together by chemical bonds.
Two or more elements chemically bonded together in fixed proportions.
What is an atom
THe smallest particle we can break a substance into
What is a molecule?
more than one atom chemically bonded together
What is a mixture>
More than one substance (elements or compounds) present but not chemically bonded
In an atom the number of electrons is equal to the number of protons. True or false
true
Where is the mass in an atom concentrated
THe nucleus
Name the 4 state symbols
s= solid
l= liquid
g= gas
aq= aqueous
WHat is aqueous
WHen a solute is dissolved in a solvent of water
Explain a method for paper chromatography
-A spot of the mixture (pen ink) is placed on the bottom of the chromatography paper
-The chromatography paper is placed in the solvent (water)
-Solvent (water) soaks up through the paper
-THe different dyes in the ink will have different solubilities
-The more soluble the dye is, the further it will move up the paper
-THe picture is called a chromatogram
Why do you draw the start line of paper chromatography in pencil
PEncil marks are insoluble and won’t dissolve in the solvent
Explain why you would be able to collect a more concentrated sample of ethanol from a mixture of water and ethanol using fractional distillation than using simple distillation
In fractional distillation you separate the water and ethanol
-In simple distillation the water and ethanol are not separated.
-In simple they both end up in the condenser
-In fractional the water remains in the round bottom flask and the ethanol ends up in the condenser
What are the relative masses of:
-proton
-electron
-neutron
proton: 1
electron: 0
neutron: 1
What was the plum pudding model and who came up with it
JJ Thomson put forward a model that showed the atom as a ball of positive charge with electrons (plums) stuck inside
What experiment did Rutherford, Geiger and Marsden carry out?
Alpha particle scatterig experiments
How did Rutherford prove the plum pudding model wrong.
He fired positively charged alpha particles at an extremely thin sheet of gold. In the experiment they expected particles to pass straight through the sheet or be slightly deflected.
This was because it was thought that the positive charge of each atom was thought to be very spread out through the ‘pudding’ of the atom.
Most particles did go straight through, however more were deflected than expected.
A small number were deflected backwards so the plum pudding model couldn’t be correct.
THis is because some particles were deflected back by the nucleus but most went through the empty space of the atom.
He proved the existence of protons
What was Rutherford’s model
THe nuclear model.
He proposed that electrons must orbit the nucleus in a cloud and the nucleus contains dense positively charged protons. (no neutrons)
Why is the total mass of products formed in a reaction equal to the total mass of reactants?
Law of conservation of mass
What did Bohr discover
-There could be no dense cloud of electrons around the nucleus as Rutherford described as it would be attracted to the nucleus and cause the atom to collapse
What did Bohr propose
He proposed that electrons orbited the nucleus in fixed shells
-Each shell being a fixed distance from the nucleus
-His theory of atomic structure was supported by many experiments and helped many scientists’ observations of the time
WHat experiments did Bohr do
Heated up atoms noticing that different atoms gave out different colours (amount of energy) as they cooled down.
What did James Chadwick discover
Neutrons
What did John Dalton describe atoms as
solid spheres. these spheres made up different elements
What does the atomic number show
How many protons
How many electrons
What does the mass number or relative atomic mass show
number of protons and neutrons
How do you find the number of neutrons
no. neutrons = mass no. - atomic no.
Work out the number of neutrons in Chlorine (35, 17)
18
35-17= 18
Why do atoms have no charge
THey have equal numbers of protons and electrons.
THerefore the charges balance out
What is an ion
An ion is a charged atom or group of atoms
What happens when an atom loses electrons
It becomes a positively charged ion
What happens when an atom gains electrons
It becomes negatively charged ion
How do you determine whether an atom will lose or gain electrons?
Whether it requires more energy to lose or gain
What happens when Lithium (3, 7) loses one electron
It forms a positive ion with 3 protons, 4 neutrons, 2 electrons
What is an isotope
a different form of the same element with the same number of protons but different number of neutrons
What is different about an isotope
-Same atomic number, different mass number
-Identical chemical properties but different physical properties
Name the sub-atomic particles in the nucleus of an atom
protons and neutrons
What does filtration separate
Insoluble solids from liquids
Name an example of a situation where filtration could be used
Sand and water
Name 2 methods for separating soluble solids from solutions
-evaporation
-crystallisation
Describe a method for evaporation
-Pour solution into an evaporating dish
-Slowly heat the solution using a bunsen burner. The solvent will evaporate and the solution will get more concentrated.
-Eventually crystals will start to form
-Keep heating the evaporating dish until all you have left are dry crystals
Describe a method for crystallisation
-Pour solution into an evaporatingdish and gently heat the solution
-Some solvent will evaporate and the solution will get more concentrated
-When some of the solvent has evaporated, or when you see crystals start to form (the point of crystallisation), remove the dish from the heat and leave the solution to cool
-The salt will start to form crystals as it becomes insoluble in the cold, highly concentrated solution
-Filter the crystals out of the solution and leave them in a warm place to dry
-You could use aa drying oven or a desiccator
Describe a method to separate rock salt.
Rock salt is a mixture of salt and sand.
-Salt is soluble in water but sand isn’t.
1. Grind mixture so salt crystals are small
2. Put the mixture in water and stir. Salt will dissolve but sand won’t
3. Filter the mixture to collect the sand.
4. Evaporate the water from the salt so that it forms dry crystals
When is distillation used?
Separating mixtures that contain liquids
What is the difference in what simple and fractional distillation separate
SImple- separate solutions
fractional- mixture of liquids
Describe a method for simple distillation
-Simple distillation is used when separating out a liquid from a solution
–The solution is heated. The part of the solution with the lowest boiling point evaporates first.
-The vapour is then collected, condenses and is collected
-The rest of the solution is left behind in the flask
-You can use simp. distillation to get pure water from sea water. The water evaporates and eventually just salt is left in the flask
What is the problem with simple distillation
You can only separate things with very different boiling points
Describe a method for fractional distillation
-A mixture of liquids. e.g crude oil
-Put mixture in a flask and stick a fractionating column on top, then heat it
-THe different liquids will all have different boiling points- so will evaporate at different temperatures
-The liquid with the lowest boiling point evaporates first. When the temp. on the thermometer matches the boiling point of this liquid, it will reach the top of the column
-Liquids with higher boiling points might also start to evaporate. But the column is cooler towards the top. So they will only get so far up before condensing back towards the flask
-When the first liquid has been collected, you raise the temperature until the next one reaches the top.
An atom of nitrogen has an atomic number of 7 and a mass number of 14, give the number of electrons, protons, and neutrons
protons- 7
electrons- 7
neutrons- 7
A substance consists of atoms which all have the same number of protons and electrons but different neutrons. Explain why this is an element
It’s the number of protons in an atom that determin what type of atom it is, so if all the atoms have the same number of protons then the subtance is an element
An isotope of iron, Fe, has a mass number of 56, and an atomic number of 26, give the number of electrons protons and neutrons
electrons = protons = 26
neutrons = 56-26 = 30
