2.1 - Atomic Structure And Isotopes

Question 1

What are the 3 important things to remember with atoms?

Answer 1

• No. of protons and electrons in an atom are always equal
• The no. Of energy levels in an atom = its period number
• the no. Of electrons in an atoms outer energy level = its group number

Question 2

Define isotope

Answer 2

Atoms of the same element with the same number of protons but a different number of neutrons and different mass number

Question 3

What are the similarities and differences of isotopes?

Answer 3

• same chemical properties
• same physical properties
• different masses
• The mass number of an isotope is known as its relative isotopic mass

Question 4

Define ion

Answer 4

An atom or molecule with a net electronic charge due to the loss or gain of electrons

Question 5

Why do ions form?

Answer 5

When atoms lose or gain electrons to create electronic stability by creating a fuller outer energy level

Question 6

What do metals do?

Answer 6

Lose electrons to form positive ions

Question 7

What do non metals do?

Answer 7

Gain electrons to form negative ions

Question 8

Define relative atomic mass

Answer 8

The weighted mean mass of an atom of a element compared to 1/12th of the mass of an atom of carbon 12

Question 9

Define relative molecular mass

Answer 9

The weighted mean mass of a molecule compared with 1/12th of the mass of an atom of carbon 12

Question 10

Define relative formula mass

Answer 10

The weighted mean mass of a formula unit compared to 1/12th of the mass of an atom of carbon 12

Question 11

What is m/z?

Answer 11

Mass to charge ratio

Question 12

What was stated in daltons atomic theory?

Answer 12

• atoms are tiny particles made of elements
• atoms cannot be divided
• all the atoms in an element are the same
• atoms of one element are different to those of other elements

Question 13

What did Thompson discover about electrons?

Answer 13

• they have a negative charge
• they can be deflected by magnet and electric field
• they have very small mass

Question 14

Explain the plum pudding model?

Answer 14

Atoms are made up of negative electrons moving around in a sea of positive charge

Question 15

What were Rutherford proposal after the gold leaf experiment?

Answer 15

• most of the mass and positive charge of the atom are in the nucleus
• electrons orbit the nucleus
• most of atoms volume is the space between the nucleus and the electrons
• overall positive and negative charges must balance

Question 16

Explain the current model of the atom

Answer 16

• protons and neutrons are found in the nucleus
• electrons orbit in shells
• nucleus is tiny compared to the total volume of atom
• most of atoms mass is in the nucleus
• most of the atom is empty space between the nucleus and the electrons

Question 17

Define relative istopic mass

Answer 17

The mass of an atom of an isotope compared with 1/12 th of the mass of an atom of carbon-12

Question 18

What 2 assumptions are made when calculating mass number?

Answer 18

1. Contribution of the electron is neglected
2. Mass of both proton and neutron is taken as 1.0 U

Question 19

What are the uses of mass spectrometry?

Answer 19

• identify unknown compounds
• find relative abundance of each isotope of an element
• determine structural information

Question 20

How does mass spectrometer work?

Answer 20

• sample is made into positive ions
• they pass through the apparatus and are separated according to mass to charge ratio
• A computer analyses the data and produces mass spectrum

Question 21

What are the 4 elements that don’t tend to form ions and why?

Answer 21

• Beryllium, Boron , Carbon and silicon
• requires a lot of energy to transfer outer shell electrons

Question 22

What are molecular ions?

Answer 22

Covalently bonded atoms that lose or gain electrons

Question 23

What is the charge of an ammonium ion?

Answer 23

+1

Question 24

What is the charge of a hydroxide ion?

Answer 24

-1

Question 25

What is the charge of a nitrate ion?

Answer 25

-1

Question 26

What is the charge of a carbonate ion?

Answer 26

-2

Question 27

What is the charge of a sulfate ion?

Answer 27

-2

Question 28

What is an empirical formula?

Answer 28

Simplest whole number ratio of atoms of each element present in a compound

Question 29

What is meant by the term weighted mean mass ?

Answer 29

The mean mass taking into account the relative abundancies of the isotopes