What makes sodium sodium? — questions

1. state

Match each statement to the particle it describes.

Write the number of the matching option.

1. Proton
2. Neutron
3. Electron

• 1. It has a relative charge of +1.: ______
• 2. It is in the nucleus and has no charge.: ______
• 3. Its relative mass is only 1/1840.: ______
• 4. It is found in shells around the nucleus.: ______
• 5. Its number decides which element the atom is.: ______

Why is almost all the mass of an atom in its nucleus?

Nudge (only if you are stuck): Look at the table of the three particles: where each one is, its relative charge and its relative mass.

2. deduce

The symbol shows an atom of fluorine. Deduce the numbers of protons, neutrons and electrons in the atom.

Protons: ______________ unit ________

Neutrons: ______________ unit ________

Electrons: ______________ unit ________

Nudge (only if you are stuck): The bottom number is the proton number. The top number counts protons and neutrons together.

3. identify / explain

A sodium atom has 11 protons, 12 neutrons and 11 electrons. Which of these changes would give an atom or ion of a different element?

Tick every correct statement.

• 1. Take away one electron.
• 2. Add one neutron.
• 3. Add one proton.
• 4. Add two electrons.
• 5. Take away one proton.
• 6. Take away one neutron.

Explain why taking away an electron doesn't change the element.

Nudge (only if you are stuck): For each change, ask: does the number of protons change?

4. deduce

A particle has 20 protons, 20 neutrons and 18 electrons. Deduce (a) its proton number, (b) its mass number and (c) its charge.

(a) Proton number: ______________ unit ________

(b) Mass number: ______________ unit ________

(c) Charge, sign first (e.g. +1): ______________ unit ________

Nudge (only if you are stuck): Proton number counts protons only; mass number counts protons and neutrons. Charge = protons − electrons.

5. describe / explain

An atom of potassium has proton number 19 and mass number 39. (a) Describe the structure of this atom: state how many of each particle it has and where each kind of particle is. (b) Explain why the atom has no overall charge. (c) Explain why the electrons make almost no difference to the mass of the atom.

(a) The particles, how many of each, and where they are

(b) Why the atom has no overall charge

(c) Why the electrons hardly add to the mass

Nudge (only if you are stuck): Use the two numbers for (a). For (b), compare the charges of the particles. For (c), use the relative masses.

6. state / deduce / explain

The most common hydrogen atom has proton number 1 and mass number 1. (a) State the numbers of protons, neutrons and electrons in this atom. (b) A hydrogen ion, H⁺, has a charge of +1. Deduce how many electrons it has. (c) Chemists often call H⁺ ‘a proton’. Explain why.

(a) Protons, neutrons and electrons in the atom

(b) Electrons in H⁺, with your working

(c) Why H⁺ can be called a proton

Nudge (only if you are stuck): For (b), use charge = protons − electrons. For (c), list what is left in H⁺.