Topic 1 Flashcards
True or false, all atoms have the same amount of electrons as protons
True
The atomic number (bottom number) tells you what
Number of protons in an atom
The mass number (top number) tells you what
The total number of neutrons and protons
What are isotopes
Isotopes are different forms of the same element which have the same number of protons but a different number of neutrons
What is a compound
Substances formed of two or more elements where the atoms are in fixed proportions and held together by chemical bonds
What is ionic bonding
When metal atoms lose electrons to form positive ions and the non metal atoms gain electrons to form negative ions. The opposite charges of the ions mean that they are strongly attracted to each other
What is covalent bonding
Covalent boning occurs between two non metals when the atoms share electrons
What is a mixture
Elements or compounds mixed together. They are easy to separate as there is no chemical bonding between elements/compounds
Explain how to separate a mixture with paper chromatography (6)
•Draw a pencil line on some filter paper
•Add a spot of the ink to the line and place the sheet on a beaker of solvent e.g water
•Make sure ink isn’t touching the solvent and put a lid on top of the container to stop it from evaporating
•The solvent will seep up the paper and carry the ink with it
•As the ink moves up the paper each different dye will begin to separate as they move at different rates
What is filtration used for
Filtration is used to separate insoluble solids from liquids. Filter paper is folded into a cone shape and mixture of solid and liquid is poured through leaving the solid behind.
What are the two ways to separate soluble solids from solutions
Evaporation
Crystallisation
Explain Evaporation
•Pour solution into evaporating dish
•Slowly heat solution. The solvent will evaporate and the solution will get more concentrated
•Keep heating evaporating dish until the crystals form
Explain Crystallisation
•Pour solution into evaporating dish and gently heat. The solvent will evaporate and the solution will become more dense
•Once you see crystals start to form remove the dish from the heal and leave it to cool
•The salt should start to form crystals as it becomes insoluble in the cold
•Finally, filter crystals out of solution and leave them in a warm place to dry
Explain simple distillation
Simple distillation is used to separate out a liquid from a solution
•The solution is heated, the part of the solution with the lowest BP evaporates first
•The vapour is then cooled and condenses and is collected
•The rest of the solution is left behind in the flask
What are the limitations of simple distillation
Simple distillation can only separate substances with very different BP if temperature goes higher than the BP of the substance with the higher BP they will mix again
Explain fractional distillation
Fractional distillation is used to separate a mixture of liquids even if BP are close together
•Put mixture in a beaker and place a fractionating column on top
•Heat the mixture, as the liquid have different BP they will evaporate at different times
•The liquid with the lowest BP evaporates first. The other liquids may start to evaporate but the fractionating column is cooler at the top so they will condense before they reach the top, running back down towards the flask
•When the first liquid is collected you can raise the temperature to the BP of the next liquid with the lowest BP
What was the plum pudding model
Made by JJ Thomas, the plum pudding model showed the atom as a ball of positive charge with electrons stuck in it
Who proved the plum pudding model wrong and how did they do it
Rutherford proved the plum pudding model wrong using the alpha particle scattering experiment leading to the nuclear model of the atom
What was Rutherfords nuclear model
Rutherfords nuclear model showed there is a tiny positively charged nucleus with a cloud of negatively charged electrons surrounding it so most of the atom was actually empty space
What was Bohr’s nuclear model
Niels Bohr’s nuclear model of the atom suggested that all the electrons were contained in shells. He proposed that the electrons orbit the nucleus in fixed shells and aren’t anywhere in between.This model is very similar to the modern day accepted version.
How many electrons are in the first 3 shells
1st=2
2nd=8
3rd=8
How were early periodic tables arranged
By order of atomic weight
Dimitri Mendeleev did what to the periodic table
Dimitri Mendeleev changed the order of the periodic table at the time, he put the elements mainly in order of atomic weight but did switch the order if the properties meant it should be changed. He also left gaps in the periodic table he made to make sure elements with similar properties stayed in the same groups. These gaps allowed Mendeleev to predict the properties of the undiscovered elements. When these elements were later discovered and found to have similar properties to that of which Mendeleev predicted, it helped confirm Mendeleev idea.
All metals have metallic bonding which means they all share similar base physical properties such as:
Strong but malleable
Good conductors of heat and electricity
High BP and MP
Trends of group 1 elements (Alkalis)
As you go down the group:
•Reactivity increases as the outer electron can be lost more easily
•Lower MP and BP
•Higher relative atomic mass
Elements in group 7 are known as what
Halogens
Trends for the halogens are
As you go down the group:
•Reactivity decreases as it is harder to gain extra electron
•Higher MP and BP
•Higher RFM/Relative atomic mass
Group 0 Elements are known as
Noble gases
Group 1 elements are known as
Alkali metals
Noble gases are what
Noble gases are inert, they don’t easily react due to the full outer shell of electrons. They exist as monoatomic gases, single atoms not bonded to each other. They are colourless and non flammable.
What is the trend for noble gases
As you go down the group, they have higher BP
