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

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Presentation on theme: "GCSE Chemistry AQA Specification Unit 1: Chemistry 1 C1.1 Fundamental ideas in chemistry C1.1.1 Atoms."— Presentation transcript:

1 GCSE Chemistry AQA Specification 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 Neutrons, which have no charge Electrons, which are negatively charged Nucleus

3 The Atom 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 orbital

4 The Atom The electrical charge of each particle can be written in a ‘relative electrical charge’ table Name of particleCharge Proton +1 (positive) Neutron 0 (neutral) Electron -1 (negative)

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

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

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

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 has six protons in the nucleus, therefore it has six 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 carbon So we can say that atoms have no overall electric charge 6 protons 6 electrons oxygen 8 protons 8 electrons sodium 11 protons 11 electrons 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 – – – – – –

10 Orbitals 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 second can hold up to 8. The third can also hold up to 8. 1 st orbital 2 nd orbital 3 rd orbital

11 Orbitals 1 st orbital 2 nd orbital 3 rd 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 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 Drawing elements

13 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 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: = 11 X X XX X X X XX XX You can draw electrons as a cross and it’s also best to draw them in pairs

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

16 Drawing elements 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 carbonoxygen sodium 2, 42, 62, 8, 1 There are two electrons on the first energy level and four on the second 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 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. However, if we look at sodium, the Latin word for this element is ‘natrium’ so the chemical symbol is ‘Na’ oxygencarbon sodium CONa Carbon is ‘C’ and oxygen is ‘O’


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