Ions Simulations

An aurora forms when charged particles from the Sun create ions in the upper atmosphere.

1. Ions

Charging up

What happens when a neutral atom gains electrons? We can investigate this
question using a simple interactive.

1. Start the interactive below by selecting Atom in the main menu.

2. Open the Net Charge panel on the right hand side.

3. Drag in 6 protons to the spot marked X.

4. Drag in 6 electrons to the blue dashed lines. The result is shown on

the right.

Question 1

Apply: Now add one more electron. What is the new net charge?

+1

0

-1

I'm not sure

Question 2

Analyze: Use your knowledge of the charges of protons and electrons to explain
the new net charge.

Ions

In the structure of an atom, the protons and neutrons are located in the nucleus at the centre. But the electrons are outside the nucleus and can therefore be removed
much more easily. Electrons can also be transferred from one atom to another.

When a neutral atom gains or loses electrons, the number of protons stays the same. The balance between positive and negative charges is lost. The result is a particle
with an overall positive or negative charge. This is called an ion.

Left: The lithium-ion batteries in smartphones work by moving around ions of the element lithium. Right: Mineral water contains ions of many

different elements, including sodium, calcium and magnesium.

Each element has its own symbol – for example, O for oxygen and Na for sodium. An ion is represented by the element symbol followed by the overall charge in

superscript.

For example, O2- represents an oxygen ion with a charge of negative 2. This is formed when a neutral oxygen atom gains two electrons.

There are two types of ions:

Negative ions form when a neutral atom gains electrons, so it has more electrons than protons. For

example, Cl- is a chlorine ion that has one extra electron compared to the neutral chlorine atom.

Positive ions form when a neutral atom loses electrons, so it has more protons than electrons.

For example, Ca2+ is a calcium ion that is missing two electrons compared to the neutral calcium atom.

An electrical attraction

Electrons can be transferred from one atom to another by simply rubbing two objects together. This creates an imbalance of electrical charges between the two objects,
known as static electricity.

We can investigate this phenomenon using another interactive.

1. In the interactive below, drag the balloon and rub it against the sweater. Observe what happens to the positive and negative charges in the two objects.

2. Investigate what happens when you let go of the balloon near the sweater and near the wall.

Question 10

Understand: After rubbing the balloon against the sweater, the balloon:

Hint: Select more than one answer.

was attracted to an object with positive charge

repelled an object with positive charge

had lots of extra electrons

repelled electrons in the wall

I'm not sure

Question 11

Analyze: Which two phrases summarize the interactions between charged particles
or objects?

Opposite charges attract

Opposite charges repel

Like charges attract

Like charges repel

I'm not sure

Question 12

Evaluate: Marianne argues that the electrons in an atom should repel each other because they all have a negative charge. So they should fly off into space rather
than staying in the atom.

Use your knowledge of the atom's structure and the charges of subatomic particles to suggest a reason why electrons tend to stay in the atom.

Question 13

I used to think...

Reflection

Reflect on how your thinking has changed since the beginning of the lesson. Do you have a better understanding of
atoms?

Explain what you used to think, and what you think now.

Question 14

But now I think...