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GCSE Chemistry

AQA Specification. GCSE Chemistry. Unit 1: Chemistry 1. C1.1 Fundamental ideas in chemistry. C1.1.1 Atoms. The Atom. An atom consists of three main particles. Protons, which are positively charged. Nucleus. Neutrons, which have no charge. Electrons, which are negatively charged.

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GCSE Chemistry

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  1. AQA Specification GCSE Chemistry Unit 1: Chemistry 1 C1.1 Fundamental ideas in chemistry C1.1.1 Atoms

  2. The Atom An atom consists of three main particles Protons, which are positively charged Nucleus Neutrons, which have no charge Electrons, which are negatively charged

  3. The Atom orbital The electrons constantly fly around the nucleus The orbital shows us where we are most likely to find the electrons at any given moment in time

  4. The Atom The electrical charge of each particle can be written in a ‘relative electrical charge’ table

  5. Elements carbon 6 protons 6 neutrons 6 electrons Atoms can have different numbers of particles If an atom has six protons, six neutrons and six electrons, it is a carbon atom. Carbon is an element

  6. Elements oxygen 8 protons 8 neutrons 8 electrons If we add two more of each particle… Two more protons This is an oxygen atom Two more neutrons Oxygen is a different element to carbon Two more electrons

  7. Elements sodium 11 protons 12 neutrons 11 electrons If we add even more particles… Three more protons This is a sodium atom Four more neutrons Sodium is a different element to carbon and oxygen Three more electrons

  8. Particles So the three particles which make up an atom are the protons, electrons and neutrons The number of protons is always the same as the number of electrons in an atom

  9. Particles carbon oxygen sodium + + + + + + – – – – – – 6 protons 6 electrons 8 protons 8 electrons 11 protons 11 electrons Carbon has six protons in the nucleus, therefore it has six electrons flying around the outside Oxygen has eight protons in the nucleus, therefore it has eight electrons flying around the outside Sodium has eleven protons in the nucleus, therefore it has eleven electrons flying around the outside Electrons are negative, and protons and positive. If you have the same number of positive and negative particles, you have no overall charge So we can say that atoms have no overall electric charge

  10. Orbitals 1st orbital 2nd orbital 3rd orbital You may have noticed some atoms have more orbitals Each orbital can only hold a certain number of electrons The first orbital can hold up to 2. The third can also hold up to 8. The second can hold up to 8.

  11. Orbitals 1st orbital 2nd orbital 3rd orbital So the more electrons an atom contains, the more orbitals it needs to house them all Orbitals can also be known as shells or energy levels

  12. Drawing elements If you are asked to draw an element, firstly you need to find out how many electrons it has. Let’s take sodium for example We know it has 11 electrons in its orbitals

  13. Drawing elements When you draw elements yourself you won’t need to draw the protons and neutrons, so the nucleus can be drawn as a circle in the centre Then you need to draw the orbitals. Don’t forget how many electrons can fit on each one. 2, 8, 8

  14. Drawing elements You can draw electrons as a cross and it’s also best to draw them in pairs X X X X X X X X X X X For sodium you need a total of 11 electrons. That means two on the first shell Eight on the second shell And just one on the third shell: 2+8+1 = 11

  15. Drawing elements X X X X X X X X X X X X X X carbon oxygen So, carbon would be drawn like this, with six electrons And oxygen like this, with eight electrons

  16. Drawing elements There are two electrons on the first energy level and four on the second energy level sodium carbon oxygen 2, 4 2, 6 2, 8, 1 In addition to drawing the elements you could also describe the electronic structure underneath by saying how many electrons there are on each energy level

  17. Element names There are around 100 known elements in the universe and each one is represented by a ‘chemical symbol’ The chemical symbol is made up of one, two or sometimes three letters. The first letter is always a capital, and any other letters are written in lowercase

  18. Element names carbon oxygen sodium C O Na The chemical symbols come from the Latin word for the element. Sometimes the Latin word is similar to the English word so you can easily guess the element. Carbon is ‘C’ and oxygen is ‘O’ However, if we look at sodium, the Latin word for this element is ‘natrium’ so the chemical symbol is ‘Na’

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