1 Atomic Structure - Periodic Table Flashcards
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?
Mass number - atomic number
How are the electrons arranged in atoms?
Orbiting the nucleus in shells
How many electrons can go in the first shell?
2
How many electrons can go in the second and third shells?
8
What are groups in the periodic table?
The columns, 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 in 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
What is an ion?
an atom which has lost or gained electron(s)
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!)
Name the first 5 elements in the periodic table
Hydrogen, Helium, Lithium, Beryllium, Boron
Name the first 10 elements in the periodic table
Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon
Name the first 15 elements in the periodic table
Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminium, Silicon, Phosphorus
Name the first 20 elements in the periodic table
Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulfur, Chlorine, Argon, Potassium, Calcium
What are the elements in group 1 called?
Alkali Metals
How does the reactivity of the group 1 alkali metals change as you move down the group?
They become more reactive
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?
Sodium
What is more reactive, chlorine or bromine?
Chlorine
Define inert
Unreactive
Explain why the noble gases are inert
They have full outer 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 as you move down the group
What state is fluorine at room temperature?
Gas
What state is chlorine at room temperature?
Gas
What state is bromine at room temperature?
liquid
What state is iodine at room temperature?
solid
Balance the equation: Li + H?O ? LiOH + H?
2Li + 2H? ? 2LiOH + H?
Balance the equation: K + H?O ? KOH + H?
2K + H? ? KOH + H?
Name LiOH
Lithium hydroxide
Name KOH
Potassium hydroxide
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 + I?
Iodine is less reactive than bromine so cannot displace it
Balance the below equation and explain why it is a displacement reaction: KBr + Cl? ? KCl + Br?
2KBr + Cl? ? 2KCl + Br? , 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, more 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
What happens to the number of electon shells as you move down the periodic table?
The number of electron shells increases