# Atoms and Bonding hollie mcintosh
Get Started. It's Free Atoms and Bonding ## 3. Valency

### 3.1. The valency of an atom tells you the number of single electrons for sharing

3.1.1. Group One - Valency of 1

3.1.2. Group Two - Valency of 2

3.1.3. Group Three - Valency of 3

3.1.4. Group Four - Valency of 4

3.1.5. Group Five - Valency of 3

3.1.6. Group Six - Valency of 2

3.1.7. Group Seven - Valency of 1

3.1.8. Group Eight / Zero - Valency of 0

## 4. Formula 1, 2 & 3

### 4.1. Formula 1

4.1.1. This formula is used to tell you the number of single electrons for sharing by using valency

4.1.1.1. Valency is used to work out a formula

4.1.2. For example: Hydrogen Nitride - Hydrogen has a valency of 1 and Nitrogen has a valency of 3, they swap and make the formula; H3N

### 4.2. Formula 2

4.2.1. This formula is used to tell you the number of single electrons for sharing WITHOUT using valency

4.2.1.1. This formula uses hidden numbers in the names of the elements

4.2.2. For example: Nitrogen trioxide , tri is the hidden word = NO3

### 4.3. Formula 3

4.3.1. This formula is used for getting valency from transition metals

4.3.1.1. The name always contains a Roman number

4.3.1.1.1. 1 - i

4.3.1.1.2. 2 - ii

4.3.1.1.3. 3 - iii

4.3.1.1.4. etc.

4.3.2. For example: Iron (iii) fluoride = FeF3

## 6. Isotopes

### 6.1. Isotopes of an element have the same number of protons but a different number of neutrons

6.1.1. Isotopes have the same atomic number but different mass numbers

## 7. Electron Arrangement

### 7.1. Electrons are arranged in shells

7.1.1. The first shell can hold 2 electrons

7.1.2. The second shell can hold 8 electrons

### 7.2. The number of electrons in the outer shell = group number

7.2.1. Atoms in the same group have the same outer electrons, they react in a similar way to each other

### 7.3. Electron arrangement for Magnesium is; Mg 2)8)2

7.3.1. Magnesium has 12 electrons

7.3.2. Calcium is similar to magnesium as its Electron arrangement is; 2)8)8)2

## 8. Atom Code

### 8.1. Atom code is the name of the method describing how to work out the Atomic number, mass number and number of protons

8.1.1. Number of protons

8.1.1.1. The number of protons = The number of electrons

8.1.2. Atomic Number

8.1.2.1. Atomic number = How many protons

8.1.3. Mass Number

8.1.3.1. Protons + Neutrons

## 10. The Periodic Table

### 10.1. The Alkali Metals

10.1.1. They are found in column one on the Periodic Table

10.1.2. Lithium, Potassium and Francium are all found in this group

10.1.3. This group is known as Group One

10.1.4. The Alkali Metals are called this as they are all alkaline

10.1.5. Every element in the group will turn blue when a pH indicator is added to it

10.1.6. The most reactive element of this group is at the bottom of the column

### 10.2. The Halogens

10.2.1. They are found in column seventeen on the Periodic Table

10.2.2. Bromine, Fluorine and Iodine are all found in this group

10.2.3. This group is known as Group Seven

10.2.4. The Halogens are called this because of the Greek word 'Halogen' which means salt maker

10.2.5. All elements in The Halogens are all poisonous and have a colourful reaction

10.2.6. The most reactive element of this group is at the top of the column

### 10.3. Noble Gases

10.3.1. They are found in column eighteen on the Periodic Table

10.3.2. Helium, Neon and Argon are all found in this group

10.3.3. This group is known as Group Eight/Zero

10.3.4. The Noble Gases are called this because every element in the group is a gas

10.3.5. All elements in the Noble Gases are very unreactive and are all poor conductors of both electricity and heat

10.3.6. The most reactive element of this group is at the top of the column

## 11. Atoms

### 11.1. Atoms are made up of three parts

11.1.1. Protons

11.1.1.1. Positive

11.1.1.2. Mass of 1

11.1.1.3. Charge of +1

11.1.1.4. Found in the nucleus

11.1.2. Neutrons

11.1.2.1. Neutral

11.1.2.2. Mass of 1

11.1.2.3. Charge of 0

11.1.2.4. Found in the nucleus

11.1.3. Electrons

11.1.3.1. Negative

11.1.3.2. Mass of 0

11.1.3.3. Charge of -1

11.1.3.4. Found outside the nucleus

### 11.2. You don't get an electric shock from atoms as the positive protons and the negative electrons balance each other out

11.2.1. 2 + (-2) = 0

## 12. Compounds

### 12.1. Each atom in the molecule gets a full outer shell

12.1.1. Methane - C + H4 = CH4

12.1.2. Water - H2 + O = H2O