2.1.2 Atomic Structure

Question 1

What are isotopes?

Answer 1

1. Atoms of the same element with different numbers of neutrons and different masses.
2. Mean ‘at the same place’ in Greek, because they are of the same element.

Question 2

What is the difference between atomic number and proton number?

Answer 2

1. The atomic number, Z, is the proton number and is the smaller number at the bottom of an element on the table.
2. The mass number, A, is the nucleon number and is the larger number at the top of an element on the table.

Question 3

What and why is the overall charge of any isotope, produce and example.

Answer 3

1. The overall charge is 0;
2. This is because isotopes of the same element have the same number of charged particles, but a different number of neutrons which have no charge.
3. Eg: in the three isotopes of Carbon.
4. The overall charge is 0 because proton n. still = electron no.

Question 4

In an isotope of x element, what is the effect on mass number and atomic number and why?

Answer 4

1. Atomic number stays the same: this is the no. of protons which has not changed.
2. The mass number changes because the number of protons has changed.

Question 5

How and why do different isotopes of the same element react?

Answer 5

Different isotopes of the same element react in the same way because:

1. Reactions involve electrons, and isotopes have the same no. and arrangement of electrons.
2. Neutrons make no difference to chemical reactivity (which is what is different in isotopes).

Question 6

Why are ions charged?

Answer 6

They have unbalanced nos of protons and electrons (charged particles), and so the charges no longer cancel each other out.

Question 7

Why would I form a + ion and not a - ion?

Answer 7

1. A + ion has one electron fewer than its no. of protons (has lost an electron);
2. A - ion has one electron more than its no. of protons (has gained an electron);

Question 8

What is special about a neutral atom?

Answer 8

It has the same no. of protons as electrons; and so is ELECTRICALLY NEUTRAL.

Question 9

What is the relative mass of an electron?

Answer 9

1/2000

Question 10

What do elements of the same isotope have?

Answer 10

1. Different masses;
2. An equal no of protons and electrons: a charge of 0;
3. Different neutron nos;