Atomic Structure And The Periodic Table Flashcards
What are all substances made out of
Atoms
What is a compound
A substance that consists of two or more different elements and are chemically combined into a fixed position
What is a reactant
The substances that react together in a chemical reaction
What is a product
The substances made in a chemical reaction
What do state symbols show
State symbols show the physical state of a substance in a reaction
What are the 4 state symbols
Solid (s)
Liquid (l)
Gas (g)
Aqueous (aq) - dissolved in water
What are ions
Charged particles are formed when atoms, groups of atoms lose or gain electrons.
How can substances in a mixture be seperated
Filtration
What is a mixture and what does this mean?
A mixture contains two or more elements or compounds that are not chemically combined.
. The chemical properties of each substance stay the same
. The substances can be separated from one another by physical processes.
Separating mixtures- No chemical reactions happen when a mixture is separated so…
No new substances are formed.
What is filtration and give an example.
A separation method that can separate an insoluble substance from a liquid, gas or solution.
Example: separating water from sand.
Why can sand be filtered from a mixture of sand and salt solution
Sand doesn’t dissolve in water. Its particles are too large to pass through the microscopic holes in the filter paper. The dissolved salt particles are small enough to pass through together with the water particles.
What is crystallisation
A separation method which separates a solid solution from a solution
What is solubility
The mass of a solute in a saturated solution at a given temperature
What is a saturated solution in terms of solubility
When no more solute will dissolve in a given volume of solvent.
What is a soluble substance
A substance is soluble if it dissolves in certain fluids
What is a solvent
A substance, usually liquid, which is capable of dissolving one of several substances
What is a solution
A mixture of one or more solutes dissolved in a solvent.
What is an insoluble substance
A substance (solid) that will not dissolve in a solvent even after mixing.
What equipment is needed for filtration
Beaker, filter paper, filter funnel, the mixture.
What equipment is needed for crystallization
Evaporating basin, beaker, gauze mat, tripod, heat resistant mat, heat source
The solubility of most substances increases as the…
Temperature increases.
Explain the crystallisation method.
- Put the solution into an evaporating basin and heat over a boiling water bath. The solution becomes more concentrated as the water in the solution evaporates.
- Stop heating before all the water has evaporated. Crystals form as the solution cools down.
- Leave the evaporating basin with its contents aside for a few days, such as a windowsill. Remove the crystals and gently pat them dry with a paper towel or filter paper.
Crystallisation- Why is a boiling water bath used instead of heating directly with a bunsen burner?
A boiling water bath heats the solution more gently and this reduces the chances of hot solids or liquids jumping out of the evaporating basin which would be unsafe.
Crystallisation- suggest one way to dry crystals over a few days other than leaving the evaporating basin for a few days.
Place the evaporating basin in a warm oven.
What is chromatography
A separation method used to separate a mixture of coloured solutes in a solution.
What are the two phases of paper chromatography and what do they mean?
- A STATIONARY PHASE that doesn’t move - usually a porous solid
- A MOBILE PHASE that moves through the stationary phase.
In chromatography, what determines how far the solution travels up the paper with the solvent?
The relative strength of the chemical bonds the solution forms with the paper in the phases.
In chromatography, the more strongly a solute bonds in the mobile phase…
The further it travels up the paper.
What equipment is used in chromatography
Tank and lid, chromatography paper, solvent
What is the method of ink chromatography
- Draw a pencil line near the bottom of the chromatography paper.
- Add a spot of the ink sample on the line.
- Place in the solvent so that the line is above the water line by a few centimetres.
- Allow the solvent to rise and remove to dry.
Chromatography- explain why the sample line must be higher than the solvent in paper chromatography
To stop it from dissolving in the solvent so it doesn’t leave the chromatography paper.
Chromatography- give two ways to determine whether two colored sports are the same substance
They will be the same colour and travel the paper the same distance on the sake chromatogram.
What are the two types of chromatography
Paper chromatography and thin layer chromatography
What is simple distillation
Separates the solvent from the solution
What does distillation rely on?
The boiling points of the components in a solution
Simple distillation- In a solution made by dissolving a solid in a liquid, the solvent boils at a lower temperature than the solute. This means that…
- The solvent evaporates and escapes the solution
- The solute is left behind and the solution gradually becomes more concentrated.
What is a solute?
a substance that dissolves in some other substance - known as a solvent - to form a solution.
In simple distillation, the solvent evaporates and travels as a vapour into a…
Condenser.
In simple distillation, what is the pure liquid solvent collected as as it leaves the condenser?
It’s collected as a distillate (a liquid product condensed into vapour during distillation)
What equipment is needed for simple distillation
Thermometer, Flask, condenser, beaker, heat source
Give one practical use of simple distillation
Drinking water can be made from sea water.
During the simple distillation of pale blue ink, the colour gradually turns dark blue.
Explain this observation.
The blue pigment stays in the ink as the solvent leaves so the ink gets more concentrated
What does fractional distillation seperate
A liquid from a mixture of liquids.
What extra piece of equipment does fractional distillation involve and where is it placed.
A fractioning column. It’s placed between the flask and the condenser.
What does the temperature gradient cause in the factionating coloumn?
- The bottom of the fractional column becomes hotter than the top
- The liquid with the lowest boiling point evaporates first and the vapour travels up the fractionating column and into the condenser where it cools and condenses.
- The liquid that leaves the column is called a fraction.
- With continued heating, liquids with higher boiling points may be collected.
Give two mixtures that can be separated by fractional distillation
Crude oil and the mixture formed by the fermentation of sugar.
Describe the function of the fractioning column in fractional distillation
The column provides a large surface area for vapours to cool, condense and evaporate again. This improves separation of different liquids in a mixture.
Describe how to separate salt and sand from a mixture of sand and salt solution
Filter to separate the sand then use crystallisation to produce salt from the filtrate.
What does filtration seperate
Insoluble solid from a liquid
What does crystallisation seperate
Solid solute from a solution
What does simple distillation seperate
Solvent from a solution
What does fractional distillation seperate
Liquid from a mixture of liquids
What does chromatography seperate
Different coloured solutes from a solution
Who discovered the electron and when and what model did it lead to?
J.J Thompson in 1897 and it lead to the plum pudding model
Explain the plum pudding model
An atom is a sphere of positive charge with negatively charged electrons in it.
Who designed an experiment to test the plum pudding model and what is it called?
Ernest Rutherford designed the alpha particle scattering experiment.
What is the idea of a nuclear model of an atom
An atom has electrons surrounding a nucleus that contains protons and neutrons.
What did Rutherford conclude from the alpha particle scattering experiment? (2)
- The mass of an atom is concentrated in the centre, in the nucleus.
- The nucleus is positively charged.
Compare the plum pudding and nuclear models of the atom
Both models have negatively charged electrons. These are embedded in a sphere of positive charge in the plum pudding model but surrounded by a positively charged nucleus in the nuclear model.
What are the 3 subatomic particles
Protons, neutrons and electrons.
What is the relative mass and charge of protons?
Mass: 1
Charge: +1
(REMEMBER: Proton - pro and pro=positive)
What is the relative mass and charge of neutrons?
Mass: 1
Charge: 0
(REMEMBER: neutron - neutral - zero)
What is the relative mass and charge of electrons?
Mass: very small
Charge: -1
Does the atomic number show the number of: protons, neutrons or electrons?
Protons.
What is the size of an atom?
1 × 10 (to the power of -10)
What is an isotope?
The same element with different atomic mass numbers.
Which number on an element is the mass mumber?
The bottom mumber
What number on an element is the atomic mass?
Top number
What does the atomic mass mumber tell you?
The total number of protons and neutrons in the nucleus.
How do you figure out the number of neutrons in an atom?
Mass number (top number) - atomic number (bottom number)
How do you find the number of protons?
The atomic number.
What is an ion?
An ion is an atom or molecule with a new electrical charge greater or less than 0.
How do ions form?
When an atom looses or gains electrons.
Complete the sentence:
___ charged ions contain ___ electrons than protons.
Positively, fewer
Complete the sentence
____ charged ions contain ___ electrons than than protons.
Negatively, more
What is relative atomic mass?
An average value that takes into account the relative abundances of all the isotopes in a sample of an element.
How can you easily check the electronic structures on the periodic table?
- Total number of electrons = atomic number.
- Number of electron shells = period number.
- Number of electrons in outer shell = group number (except for group 0)
How are elements ordered on the periodic table
Order of increasing atomic number.
What are the rows called on the periodic table
Periods
What are the columns on the periodic table called
Groups.
What properties do elements in the same group have?
- Similar chemical reactions.
- Same number of electrons on outer electron shell.
What determines the chemical properties of an element (periodic table)
The number of electrons on the outer shell (group number)
Who discovered the periodic table
Mendeleev
First, how did medeleev order elements in the periodic table
In order of increasing atomic weight
What did it mean for there to be gaps in the periodic table when Mendeleev was discovering it? (2)
- Elements with similar chemical properties were placed in the same group.
- He could make predictions of the physical and chemical properties of the unknown elements.
What did early attempts to produce periodic tables on and why was it unsuccessful?
They relied on atomic mass. It was unsuccessful because it was often inaccurate and they differed in value from the modern relative atomic masses, often too high or too low.
How can you tell if an element is an atom?
If it forms positively charges ions
How can you tell if an element is a non-metal
If it doesn’t produce positively charged ions
What bonding is between metals
Metallic bonding
(REMEMBER: metals are shiny - metal - metallic)
What bonding is between non-metals
Covalent bonding
What bonding is between a metal and a non-metal
Ionic bonding
Compare the appearance of metals and non metals.
Metals are shiny.
Non metals are dull
Compare the melting and boiling points of metals and non metals.
Metals have high melting and boiling points.
Non metals have low melting and boiling points.
Compare the density of metals and non-metals.
Metals have high density
Non-metals have low density
Compare the ability to conduct electricity and thermal energy of metals and non-metals.
Metals have good conductivity
Non-metals have poor conductivity
Describe the positions of metals and non-metals on the periodic table
Metals are found towards the bottom and left, and non-metals are found towards the top and right.
Compare the malleability of metals and non-metals.
Metals can be hammered into shapes without shattering
Non-metals shatter when hammered.
What are the elements in group 0 called?
Noble glases
True or false?
Group 0 elements are unreactive non-metals.
True
Because the outer electron shell is filled for noble gases, what does it mean? (2)
- They have little tendency to gain or lose electrons in chemical reactions.
- They have little tendency to share electrons.
Are the boiling points for noble gases very high or very low and what state does that mean they’re in at room temp?
Very low. Gases at room temperature.
Do the boiling points of noble gases decrease going up or down the group?
Down
Describe the relationship in Group 0 between boiling point and relative atomic mass
Boiling points increase as the tractive atomic mass increases.
What are group 1 elements called.
Alkali metals
What happens between alkali metals and chlorine when heated?
They react vigorously and burn to produce coloured flames to produce metal chlorides.
What colour flame does lithium produce when reacting with chlorine?
Red
What colour flame does sodium produce when reacting with chlorine?
Orange
What colour flame does potassium produce when reacting with chlorine?
Lilac - most vigorous reaction.
Do alkali metals (group 1) get more or less reactive going down the group?
Down
What do alkali metals loose in reactions with non-metals?
Their outer electron
What is produced when alkali metals and water react together?
Metal hydroxides and hydrogen
What do the first 3 elements in group 1 do when reacting with water?
They float and disappear as they react.
What does lithium do when reacting with water?
Fizzes steadily
What does sodium do when reacting with water?
Melts into a silvery ball, fizzes quickly and may burn with an orange flame.
What does potassium do when reacting with water?
Burns with a lilac flame very quickly, then pops or explodes.
Are the metal hydroxides produced during reactions between alkali metals and water soluble or insouble?
Soluble
What are group 7 elements called
Halogens
Do the melting and boiling points increase or decrease going down the group?
Increase
What state are fluorine and chlorine in at room temperature?
Gas
What state is bromine in at room temperature?
Liquid
What state is iodine in at room temperature?
Solid
What is formed when halogens react with non-metals?
Ionic compounds.
What do halogen molecules consist of and what are they joined by?
They consist of 2 atoms and are joined by a covalent bond.
Depending on the conditions, what can be formed between a halogen and a non-metal
A covalent compound
Do halogens become more or less reactive going down the group?
Less
What do halogens gain in reactions with metals.
Electrons.
When does a displacement reaction happen?
When an atom or ion replaces an existing atom or ion in a compound.
A more reactive halogen can ____ a less reactive halogen from its ___, particularly ___ in aqueous solutions.
Displace, compound, salts
What 3 elements can be dissolved in water to form aqueous solutions?
Chlorine, bromine and iodine.
