C1 Flashcards
What are atoms made from
Protons, neutrons and electrons
What is an atoms radius
0,1 nanometer
Where is the nucleus in the atom and what does it contain
Middle and contains protons and neutrons
What is the radius of a nucleus
1x10^-14
What charge is the nucleus and why
Positive charge because it contains protons and neutrons
Relative mass of proton
1
Relative mass of neutron
1
Relative mass of electeon
Very small
Relative charge of proton
1
Relative charge of neutron
0
Relative charge of electron
-1
How do you know the number of protons and electrons of an element
Atomic number (bottom number of nuclear symbol)
How do you find the mass number
Protons + nuetrons
How to find number of neutrons
Top number (mass number) - bottom number (atomic number)
What is an atoms overall charge?
0 because they have the same amount of protons and electrons
Who was the first scientist to discover an atom, what year and what did he discover
John dalton - start of 19th century
Said atoms were solid spheres
Who was the second scientist to discover an atom, what year and what did he discover
JJ Thomson - 1897 - plum pudding model, believed the atom is a ball of charge with electrons scattered
Who was the third scientist to discover an atom, what year and what did he discover
Ernest rutherford, 1909, alpha scattering experiment - mass comentrated in the centre, the nucleus is charged, most of the mass is in the nucleus. Most atoms are empty space
Who was the fourth scientist to discover an atom, what year and what did he discover
Niels bohr, 1911, discovered electrons are in shells orbiting the nucleus
Who was the 5th scientist to discover an atom, what year and what did he discover
James chadwich, 1940, discovered that there are neutrons in the nuecles
Where are electrons found in an atom
Shells
How many electrons do the first, second shell contain
2,8
What is an element
Substance made up of atoms that all have the same number of protons in their nuclues
How are compounds created
When atoms combine with other apms
If the element loses electrons it forms a
Positive ion
Is an element gains electrons it forms a
Negative ion
What is covalent bonding
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs betweenatoms
How are ions made
When electrons are transfered
Why does an element form an ion
They are trying to gain a full outershell. This is because the element is trying to becine more stable
Group 1 ionic form
+1 making a negative ion
Group 2 ionic form
+2 - negstive ion
Group 3 ionic form
+3 negative ion
Group 4 ionic form
+/-4 negative or positive ion
Group 5 ionic form
-3 positive ion
Group 6 ionic form
-2 positive ion
Group 7 ionic for
-1 positive ion
Importance of symbol equation?
Helps you see how much of each substance is involved in a reaction
Law of conservation of mass:
The total mass of the products formed in a reaction is equal to the total mass of the reactants
How can the law of conservation of mass be broken?
When reactions are carried out in open containers (e.g. test tubes or conical flasks)
Features of Compounds
-have a fixed composition
-chemical reactions must be used to seperate the elements
-chemical bonds between atoms
Features of mixtures:
-no fixed composition
-the different elements can be seperated more easily
-no chemical bonds between atoms of different substances
Filtration:
-used to seperate substances that are insoluable in a particular solvent from those are soluble in the solvent
-e.g. a mixture of sand, salt
Crystalisation:
-to obtain a pure sample of salt from the solution following filtration
Distillation:
-a solution is heated and boiled to evaporate the solvent. The vapor given off then enters a condenser. The hot vapour is cooled and condensed back to a liquid for collection
Evaporation method:
1) pour solution into evaporating basin
2) slowly heat solution
3) the solvent will evaporate and crystals will start to form
4) keep heating dish until only crystals are left
Filtration to separate rock salt method:
1) grind the mixture to make sure the salt crystals are small
2) put the mixture in water and stir until the salt dissolves (sand won’t dissolve)
3) filter the mixture and the grains of sand will collect in the filter paper (salt passes through)
4) evaporate water from salt so it forms dry crystals
Simple distillation method to separate solutions:
1) solution is heated and solution with lowest BP evaporates first
2) the vapour is cooled, condensed and collected
3) rest of solution is left in flask
What can simple distillation be used for?
To get pure water from seawater
Problem with simple distillation:
You can only seperate things with very different boiling points
