Elements

Question 1

What is an element?

Answer 1

An element is a substance made up of atoms that all have the same number of protons in their nuclei.

Question 2

What determines the type of atom?

Answer 2

The number of protons in the nucleus determines the type of atom.

Question 3

What is an example of an atom with one proton?

Answer 3

An atom with one proton is hydrogen.

Question 4

What is an example of an atom with two protons?

Answer 4

An atom with two protons is helium.

Question 5

Approximately how many different elements are there?

Answer 5

There are about 100 different elements.

Question 6

What do all atoms of a particular element have in common?

Answer 6

They have the same number of protons.

Question 7

How do atoms of different elements differ?

Answer 7

Atoms of different elements have different numbers of protons.

Question 8

How are elements commonly represented?

Answer 8

Elements are represented by a one or two letter symbol.

Question 9

What are some examples of element symbols?

Answer 9

C for carbon, O for oxygen, Mg for magnesium.

Question 10

Where do many element symbols originate?

Answer 10

Many element symbols are derived from Latin names.

Question 11

What are isotopes?

Answer 11

Isotopes are different forms of the same element with the same number of protons but a different number of neutrons.

Question 12

What stays the same in isotopes?

Answer 12

The atomic number remains the same in isotopes.

Question 13

What differs between isotopes?

Answer 13

The mass number differs due to different numbers of neutrons.

Question 14

Give an example of isotopes of carbon.

Answer 14

Carbon-12 and Carbon-13 are isotopes of carbon.

Question 15

Why is relative atomic mass used for elements?

Answer 15

Relative atomic mass is used because elements often exist as multiple isotopes with different masses.

Question 16

How is relative atomic mass calculated?

Answer 16

Relative atomic mass is calculated as the sum of (isotope abundance x isotope mass number) divided by the sum of the abundances of all isotopes.

Question 17

What is the formula for relative atomic mass?

Answer 17

Relative atomic mass = (sum of (isotope abundance x isotope mass number)) / sum of abundances of all isotopes.

Question 18

Example: How is the relative atomic mass of copper calculated?

Answer 18

For copper with isotopes Cu-63 and Cu-65: (69.2 x 63 + 30.8 x 65) / 100 = 63.6.

Question 19

Q1: Why is a substance with the same number of protons and electrons, but different neutrons, considered an element?

Answer 19

Because all atoms of that substance have the same atomic number (protons).

Question 20

Q2: Calculate the relative atomic mass of silicon, given three isotopes: Si-28 (92.2%), Si-29 (4.7%), Si-30 (3.1%).

Answer 20

Relative atomic mass = (92.2 x 28 + 4.7 x 29 + 3.1 x 30) / 100 = 28.1 (to 1 decimal place).