Atoms, Ions and Compounds

Question 1

What is the mass of an electron?

Answer 1

1/1836th of the mass of a proton

Question 2

What is the mass of a proton/neutron?

Answer 2

1

Question 3

Define atomic number

Answer 3

The number of protons in the nucleus of an atom

Question 4

Define isotope

Answer 4

Atoms of the same element with same number of protons, different number of neutrons and different masses.

Question 5

What does ‘A’ represent?

Answer 5

A is the mass number (number of protons + number of neutrons)

Question 6

What does ‘Z’ represent?

Answer 6

Z is the atomic number ( number of protons)

Question 7

Do isotopes of the same element react differently? Why?

Answer 7

No. Isotopes of same element have same number of electrons, only a different number of neutrons and therefore there is no effect on reactions of element.

Question 8

Do isotopes have different physical properties?

Answer 8

Yes. Higher mass isotopes may have higher boiling points, melting points and densities.

Question 9

What is an ion?

Answer 9

A charged atom where the number of electrons is different to the number of protons.

Question 10

What is a cation?

Answer 10

A positive ion. Number of electrons fewer than number of protons. Overall positive charge.

Question 11

What is an anion?

Answer 11

A negative ion. Number of electrons greater than number of protons. Overall negative charge.

Question 12

Why can you not add together all relative masses of proton, neutron and electron to get total mass?

Answer 12

Strong nuclear force holding together the protons and neutrons comes at the expense of a loss of a small proportion of mass

Question 13

What is the standard isotope used?

Answer 13

Carbon-12

Question 14

Define relative isotopic mass

Answer 14

The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12

Question 15

Define relative atomic mass

Answer 15

The weighted mean mass if an atom of an element relative to 1/12th of the mass of an atom of carbon-12

Question 16

What two factors does the weighted mean mass take into account?

Answer 16

Percentage abundance of each isotope

Relative isotopic mass of each isotope

Question 17

What equipment is used to calculate percentage abundance of isotopes?

Answer 17

Mass Spectrometer

Question 18

Describe process of using mass spectrometer

Answer 18

Sample placed in mass spectrometer
Sample is vaporised 
Sample is ionised to form positive ions
Ions are accelerated
Heavier ions move more slowly, isotopes are separated
Ions are detected on mass spectrum

Question 19

What does m/z signify?

Answer 19

mass to charge ratio. Relative mass of the ion/ relative charge on ion