Starter quiz
- Why do atoms form chemical bonds?
- To increase their mass.
- To achieve a full outer electron shell. ✓
- To lose all their electrons.
- To become larger in size.
-
- Which type of bond forms between atoms that have transferred electrons from one atom to another?
- Covalent bond
- Ionic bond ✓
- Metallic bond
-
- What type of elements typically form ionic bonds?
- Two non-metals.
- Two metals.
- A metal and a non-metal. ✓
-
- How many outer-shell electrons does an oxygen atom have?
- 2
- 4
- 6 ✓
- 8
- 16
-
- A ______ is a particle consisting of two or more non-metal atoms bonded together. It can be made up of the same or different elements.
- 'molecule' ✓
- Arrange the following molecules by the number of covalent bonds each has, from least to most:
- 1⇔H₂
- 2⇔O₂
- 3⇔N₂
Exit quiz
- What is a covalent bond?
- A bond between two metal atoms.
- A bond between a metal and a non-metal atom.
- A bond where two non-metal atoms share a pair of electrons. ✓
- A bond formed of ions, where atoms have transferred electrons.
-
- How many covalent bonds will an atom form if it needs three electrons to complete its outer shell?
- 1
- 2
- 3 ✓
- 4
- Not enough information is known
-
- What does a displayed formula of a covalent substance show?
- All of the atoms present in the substance. ✓
- All of the bonds between atoms. ✓
- A shorthand version of the structure, showing only some of the atoms.
- A shorthand version of the structure, showing only some of the bonds.
- Each line drawn represents a shared pair of electrons. ✓
-
- What is the purpose of a dot and cross diagram?
- To show the physical state of a substance.
- To show how chemical bonds are formed between atoms. ✓
- To represent the empirical formula of a compound.
- To show the arrangement of metal ions.
-
- A ______ is a particle consisting of a fixed number of non-metal atoms covalently bonded together.
- 'molecule' ✓
- Atoms can share multiple pairs of electrons to achieve full outer shells, leading to double or ______ covalent bonds.
- 'triple' ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- In a covalent bond, two non-metal atoms share a pair of electrons (from their outer shells).
- For every one electron needed to complete the outer shell of an atom, one covalent bond will form.
- Atoms can share multiple pairs of electrons.
- Displayed formulae of covalent substances are a model, showing lines to represent shared pairs of electrons.
Common misconception
The covalent bond is the shared pair of electrons; both electrons must come from different atoms. The central atom is responsible for the formation of covalent bonds as they want a full outer shell.
All chemical bonds are an electrostatic force of attraction between positive and negative charges. The sharing of electrons is the process by which covalent bonds are formed. Avoid using anthropomorphic analogies to explain how covalent bonds form.
Keywords
Molecule - A particle consisting of a fixed number of (two or more) non-metal atoms covalently bonded together.
Covalent bond - The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
Dot and cross diagram - Is used to show how chemical bonds are formed between atoms. The electrons from one atom are shown as dots and the electrons from the other atom are shown as crosses.
Empirical formula - Shows the simplest whole number ratio of atoms of each element in a compound.
Displayed formula - A 2D model of a covalent substance, showing all its atoms and bonds. Lines are used to represent shared pairs of electrons.