Year 9 Structure Of The Atom, The Periodic Table, Group 1, Group 7, Reactivity Series, Extraction and Uses of Metals and Testing for Ions and Gases Flashcards
The nucleus
In middle of atom
Contains protons and neutrons
Has a positive charge because if the protons
The weight of the atom is basically the weight of the nucleus
Tiny compared to rest of atom
The electrons
Move around the nucleus in energy levels called shells
Negatively charged
Tiny but cover a lot of space
The size of their orbits determines how big the atom is
Almost no mass
Protons Neutrons Electrons Atomic Number Mass Number
Protons-heavy, +ve charge Neutrons-heavy, neutral Electrons- tiny, -ve charge No. of electrons = no. of protons ATOMIC NUMBER = PROTONS MASS NUMBER = PROTONS + NEUTRONS
What is an isotope?
They are different atomic forms of the same element, and have the SAME no. of PROTONS and DIFFERENT no. of NEUTRONS
What is relative atomic mass?
It takes all STABLE ISOTOPES into account
It’s a way of saying how heavy different atoms are compared with the mass of an atom of carbon-12
It’s the average mass of all the isotopes of an element. It allows for the relative mass of each isotope and its relative abundance
How do you calculate the RAM of an element from the relative abundances of the isotopes?
Eg. Chlorine - relative mass of each isotope = 35,37
- relative abundance = 3,1
Multiply the mass of each isotope by its relative abundance
Add these together
Divide by the sum of the relative abundances
(35 x 3)+(37 x 1) / 3 + 1 = 35.5
What is a group in the periodic table?
The columns. Elements in a group all have the same number of electrons on their outer most shell
What is a period in the periodic table?
The rows. The row number tells us how many electron shells the atom will have
Metals
Elements to the left of the zig zag are metals.
They conduct electricity because they allow charge to pass through them easily
Metal oxides are basic. This means that they’ll neutralise acids.
If they dissolve, then they’ll form a pH of more that 7
Non-metals
Elements to the right of the zigzag are on metals.
They’re poor conductors of electricity
Non metal oxides are acidic.
They dissolve in water and form solutions with a pH of under 7
Why do elements in the same group have similar chemical properties?
They have the same number of electrons on their outer shell
The Nobel gases (group 0)
They are inert which means that they don’t react with much at all.
This is because they have a full outer shell of electrons, so they don’t want to give up or gain electrons to become more stable.
What happens when lithium reacts with water?
Lithium takes the longest, about 30 seconds, so it’s the least reactive group 1 metal.
The lump of lithium moves slowly around the surface of the water and fizzes until is disappears.
The solution is alkaline, and of a drop of universal indicator is added to the water before hand, the water turns purple.
lithium + water –> lithium hydroxide + hydrogen
2Li(s)+2H2O(l) –> 2LiOH(aq) + H2(g)
What happens when sodium reacts with water?
Sodium reacts with water faster than lithium does (it takes 20s) but still slower than potassium takes.
The lump of sodium moves quite quickly around the surface of the water and fizzes rapidly and it can ignite.
The solution is alkaline, and of a drop of universal indicator is added to the water before hand, the water turns purple.
sodium + water –> sodium hydroxide + hydrogen
2Na(s)+2H2O(l) –> 2NaOH(aq) + H2(g)
What happens when potassium reacts with water?
Potassium reacts the fastest, it takes about 5s, so it’s the most reactive.
The potassium reacts vigorously and burns with a lilac flame and sometimes explodes.
The solution is alkaline, and of a drop of universal indicator is added to the water before hand, the water turns purple.
potassium + water –> potassium hydroxide + hydrogen
2K (s) +2H2O(l) –> 2LiOH(aq) + H2(g)
How can we determine that the group one metals are all of the same family?
Elements in the same family will all react in a similar way and they all react vigorously with water. This reaction produces a metal hydroxide solution, which is alkaline, explaining why the group one elements are known as the alkali metals. The reaction also produces hydrogen, which is why fizzing happens.
What is the order of reactivity for group 1?
They get more reactive as you go down the group. This is because they all have one electron on their outer shell, but as you go down the group, the outermost electron is further and further away from the nucleus. This means that the attraction between the outermost electron and the nucleus becomes less. So as you go down the group, the atoms get bigger and the outer electron is more easily lost, so the metals are more reactive.
