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AQA Chemistry Topic 1 - Atomic Structure and the Periodic Table
Terms in this set (63)
The smallest part of an element that can still be recognised as that element
A substance made of only one type of atom
A substance made of two or more different atoms chemically bonded together
A substance made of more than one atom chemically bonded together (can be atoms of the same type!)
A substance made of more than one thing not chemically bonded together
State the three subatomic particles
Protons, neutrons, electrons
State the masses of the subatomic particles
Protons: 1, neutrons: 1, electrons: 0
State the relative charges of the subatomic particles
Protons: +1, neutrons: 0, electrons: -1
How are the subatomic particles arranged in an atom? (3 marks)
Protons and neutrons in the nucleus, electrons orbiting in shells
What is the plum pudding model of the atom?
A ball of positive charge with negative electrons studded into it
What did the gold foil experiment prove?
That atoms have dense nucleuses with a positive charge
What is the atomic number of an atom?
The number of protons in an atom
What is the mass number of an atom?
The number of protons + the number of neutrons in an atom
How do you calculate the number of neutrons in an atom?
Relative atomic mass - atomic number
How are the electrons arranged in atoms?
Orbiting the nucleus in shells
How many electrons can go in the first shell?
How many electrons can go in the second and third shells?
What are groups in the periodic table?
The columns going down, numbered 1, 2, 3, 4, 5, 6, 7, 0
What can the group tell you about the electrons in an atom?
How many electrons in the outer shell. E.g. carbon is in group 4 so has 4 electrons in the outer shell
What are periods in the periodic table?
The rows going across the periodic table -->
What can the period tell you about the electrons in an atom?
How many shells an atom has. E.g. carbon is in the second period so has two shells
Why did Mendeleev put some elements in groups?
Because they had similar chemical properties (e.g. they reacted violently with water)
Why did Mendeleev leave gaps in his periodic table?
For elements that had not been discovered yet that would have similar properties to the rest of the group
What is an ion?
an atom which has lost or gained an electron
How many electrons does calcium have?
20 (same as atomic number!)
How many electrons does silicon have?
14 (same as atomic number!)
How are the electrons in sulphur arranged?
2.8.6 (18 electrons total)
How are the electrons in magnesium arranged?
2.8.2 (12 electrons total)
How many electrons are in the outer shell of boron?
3 (it is in group 3!)
How many electrons are in the outer shell of phosphorous?
5 (it is in group 5!)
How many electrons are in the outer shell of sodium?
1 (it is in group 1!)
An element has three shells and three electrons in the outer shell. What element is it?
Aluminium (group 3, period 3
How many electrons are in the outer shell of Gallium?
3 (it is in group 3!)
In terms of electrons, what do group 1 elements have in common?
1 electron in the outer shell
In terms of electrons, what do group 7 elements have in common?
7 electrons in the outer shell
In terms of electrons, what do group 0 elements have in common?
Full outer shell
What is more reactive, lithium or sodium?
What is more reactive, chlorine or bromine?
Explain why the noble gases are inert
They have full outer electron shells, so do not need to gain or lose electrons
What is a trend?
A pattern in properties
State the trend in the melting points of the alkali metals
Gets lower down the group
What state is fluorine at room temperature?
What state is chlorine at room temperature?
What state is bromine at room temperature?
What state is iodine at room temperature?
Balance the equation: Li + H₂ → LiOH + H₂
2Li + 2H₂ → 2LiOH + H₂
Balance the equation: K + H₂ → KOH + H₂
2K + H₂ → KOH + H₂
Explain why the group 1 elements are called alkali metals
They are metals that form alkalis when they react with water
What is a displacement reaction?
A reaction in which a more reactive element takes the place of a less reactive element in a compound
Explain why the following reaction does not proceed: KBr + I₂
Iodine is less reactive than bromine so cannot displace it
Balance the below equation and explain why it is a displacement reaction: KBr + Cl₂ → KCl + Br₂
2KBr + Cl₂ → 2KCl + Br₂ , chlorine has displaced bromine as it is more reactive
Explain why fluorine is more reactive than chlorine
Fewer shells/electrons, less shielding (or stronger attraction from nucleus), easier to gain electrons
Explain why potassium is more reactive than lithium (3 marks)
More shells/electrons, less shielding (or weaker attraction from nucleus), easier to lose electrons
Explain why bromine is less reactive than chlorine (3 marks)
More shells/electrons, less shielding (or weaker attraction from nucleus), harder to gain electrons
Explain why sodium is less reactive than caesium (3 marks)
Fewer shells/electrons, less shielding (or stronger attraction from nucleus), harder to lose electrons
Relative Atomic Mass
Sum of protons and neutrons in the nucleus
Atomic (proton) number
Number of protons in the nucleus. Equal to the number of electrons.
Alkali metals. All have one electron in their outer shell. Increase in reactivity down the group.
Noble Gases. All have full outer shells of electrons. Unreactive.
Halogens. All have seven electrons in their outer shell. Decrease in reactivity down the group.
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