Periodic table for OCR GCSE Chemistry
This page covers the following topics:
1. Periodic table structure
2. Electronic structure
There are specific names used for some groups of the periodic table:
group 0/8 (18) → noble gases
group 1 → alkali metals
group 7 (17) → halogens
Elements in the same group have similar properties since they have the same number of electrons in their outer shell. For groups 1-2 and 3-8 it is the same as the group number. For example, phosphorus has 5 electrons in its outer shell. If you use a periodic table with 1-18 group numbers, you should convert groups 13-18 to 3-8 respectively as the aforementioned rule doesn’t necessarily apply for the groups 3-12.
As you go down a group, the elements get bigger as they gain additional shells of electrons.
The electronic structure is the way in which electrons are arranged in an atom. Electrons in atom are arranged in shells (or energy levels) surrounding the nucleus. For many atoms, the electrons in an atom occupy the shell nearest the nucleus first, until it is full.
The first shell can contain 2 electrons. For elements up to and including calcium, the second and third shells can contain 8 electrons. Their electronic structure can be written as a numbers x, y, z, where x represents the number of electrons in the first shell, y in the second and z in the third.
Each electron shell corresponds to an energy level. For example, electrons that are in the second electron shell are in the second energy level.
Transition metals are much harder than group 1 elements, and have higher melting points. But the electron configuration of group 1 elements makes them much more reactive than transition metals.
Where an element is found in the periodic table can tell you a lot about its physical and chemical properties. Most elements are metals except for the top right corner of the periodic table and hydrogen. In between metals and nonmetals we can find metaloids that have properties similar to both metals and non-metals.
Since the group an element is in indicates how many electrons are in the outer shell, it can be used to determine the ionic charge. Metals usually form positive ions with the charge of their group number and a plus (+). Nonmetals usually form negative charges with their charge being their group number minus 8.
Which element has the higher melting point, Vanadium or Potassium?
What is special about the oxidation states of transition metals?
Transition metals can adopt various oxidation states.
What is the most common charge of group 1 elements?
What is the electronic structure of sodium which has 11 protons?
The electrons in an atom occupy the shell nearest the nucleus first, until it is full. The first shell can contain 2 electrons. For elements up to and including calcium, the second and third shells can contain 8 electrons.
Sodium has 11 electrons as it has 11 protons.
Allocating these 11 electrons into the first few electron shells gives 2, 8, 1.
2, 8, 1
A lump of iron and a lump of sodium are left open to air. Which will oxidise first?
Sodium, group 1 elements are more reactive.
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