Structure of the atom

Activity 1

1. The following are atoms of hydrogen, helium and carbon.

a.

b.

c.

Fig 1.1 Protons, Electrons and Neutrons in Atoms

1. Compare the atoms in pictures a, b and c, then describe any notable similarities.
2. Identify the sub atomic particles in the hydrogen atom, helium atom and carbon shown in the pictures.
3. What are the charges of the subatomic particles from the pictures?
4. What is the location of the sub atomic particles found in the atom?

Digital Activity

Requirements

• Digital devices connected to the internet
• Exercise books
• Charts or printed materials containing information on structure of the atom
• Pens

What to do

1. Use digital media or print resources to search for information on the structure of the atoms.
2. Draw the structure of a hydrogen atom in your exercise book.
3. Share your work in class.

Learning points

• There are three main sub atomic particles in any atoms. These are protons, neutrons and electrons.
• The protons and neutrons are found in the nucleus of the atom which is found at the centre of the atom. The electrons move around the nucleus in paths known as energy levels.
• Protons are positively charged particles that are found in the nucleus.
• Neutrons are also found in the nucleus. They have no charge.
• Electrons revolve around the nucleus and are negatively charged.

Digital Activity

Requirements

• Digital devices connected to the internet
• Exercise books
• Charts or printed materials containing electron arrangement in atoms
• Pens

What to do

1. Use digital media or print resources to search for information on electron arrangement in atoms.
2. Write down your findings.
3. Share your findings in class.

Activity 4

1. Nderi, a Grade 9 learner, came across the following chart which show the electron arrangement of some atoms. In groups, study the chart and answer the questions that follow.

Fig 1.2 Electron Arrangement in Atoms

1. Count and note the number of electrons in the carbon and calcium atoms shown on the chart.
2. How many energy levels can you see in the carbon and calcium atoms.
3. How many electrons are there in the first energy level?
4. Discuss the number of the electrons in the subsequent energy levels.

Learning points

• Each energy level in an atom can hold only a certain number of electrons.
  • Lowest first energy level can hold 2 (two) electrons.
  • Second energy level can hold 8 (eight) electrons.
  • Third energy levels holds 8 electrons.
• Electron arrangement of atoms can be represented in writing using numbers and separated with dots. For example: Calcium 2.8.8.2
• The first “2” represents the number of electrons in the first energy level.
• The following “8” represents the number of electrons in the second energy level.
• The second “8” represents the number of electrons in the third energy level.
• The final “2” represents the number of electrons in the fourth energy level.

Note: The energy levels can hold less electrons if the number of electrons is less than the maximum number an energy level can hold.

Practical Activity 1

Drawing electron arrangement of common elements.

Materials

• A pair of compass
• Pencil
• Marker pen or ball pen.
• Drawing book

What to do

1. Draw two centric circles (a small circle inside a bigger circle). Label the innermost circle as nucleus or H to represent hydrogen.
2. Draw one dot or X in the outermost circle to represent electron and label the drawing as Hydrogen.

Fig 1.3 Hydrogen Atom representation

Fig 1.3 Hydrogen Atom representation

1. Draw two centric circles. Label the innermost circle as nucleus or He to represent helium.
2. Draw two dots or x in the outermost circle to represent electrons. The dots should alternate each other and label the drawing as Helium.

Fig 1.4 Helium Atom representation

Fig 1.4 Helium Atom representation

1. Draw three centric circles. Label the innermost circle as Li to represent Lithium.
2. Draw two alternate dots in the second circle.
3. Draw one dot in the third circle and label the drawing as Lithium.

Fig 1.5 Lithium Atom representation

Fig 1.5 Lithium Atom representation

1. Repeat the procedure until you have the first 20 elements.
2. Note, the second and the third levels should only hold a maximum of 8 electrons. For example,

Fig 1.6 Magnesium and Calcium atoms representations

Activity 8

1. In groups, make flash cards containing the following elements.

1. Indicate the number of electrons, protons and neutrons in each flash card.
2. Write the electron arrangement of the elements on the same flash cards.
3. õState whether the elements are metals or non metals.
4. Attach the flash cards on a manilla paper and label the chart as classification of elements into metals and non-metals.
5. Display your work in class.