Chapter 3-Atomic structure

Question 1

What is an atom?

Answer 1

An atom is the smallest piece of an element that can still be recognised as that element (it cannot be broken by a chemical reaction).

Question 2

What is a molecule?

Answer 2

A molecule is small group of two or more atoms chemically bonded (by covalent bonds). The atoms that make up a molecule can be from the same elements or different elements.

Question 3

What are the sub-atomic particles called?

Answer 3

Protons, neutrons and electrons

Question 4

What is the centre of an atom called and what are the sub-atomic particles found there?

Answer 4

The centre of an atom is called the nucleus and protons and neutrons are found there.

Question 5

Where are electrons found in an atom?

Answer 5

Electrons are found in shells orbiting the nucleus.

Question 6

What is the relative mass of proton?

Answer 6

The relative mass of a proton is 1.

Question 7

What is the relative charge of a proton?

Answer 7

The relative charge of a proton is +1.

Question 8

What is the relative mass of a neutron?

Answer 8

The relative mass of a neutron is 1.

Question 9

What is the relative charge of a neutron?

Answer 9

The relative charge of a neutron is 0.

Question 10

What is the relative mass of an electron?

Answer 10

The relative mass of an electron is 1/1836 (almost 0).

Question 11

What is the relative charge of an electron?

Answer 11

The relative charge of an electron is -1.

Question 12

What makes atoms neutral?

Answer 12

In an atom, the number of electrons (negative) is equal to the number of protons (positive) so atoms are neutral (they have no overall electrical charge).

Question 13

What is the atomic number?

Answer 13

The number of protons in an atom’s nucleus is called its atomic number or proton number.
*atomic number=number of protons

Question 14

What is the mass number?

Answer 14

The mass number (sometimes known as the nucleon number) tells us the total number of protons and neutrons in the nucleus of the atom.
*mass number=number of protons+number of neutrons

Question 15

How do you find out the number of neutrons in an electron?

Answer 15

*number of neutrons=mass number-atomic number

Question 16

How can APEMAN be used to find the number of protons, neutrons and electrons in an atom?

Answer 16

Atomic number (smallest)=
Protons=
Electrons=
Mass number (biggest)-
Atomic number (smallest)=
Neutrons

Question 17

What are isotopes?

Answer 17

Isotopes are atoms (of the same element) which have the same atomic number but different mass numbers. They have the same number of protons but different numbers of neutrons.

Question 18

Why do isotopes have the same chemical properties?

Answer 18

Their varying numbers of neutrons make no difference to their chemical reactions. The chemical properties are controlled by the number and arrangement of the electrons; that is identical for all the isotopes.

Question 19

What is Relative Atomic Mass (RAM)?

Answer 19

The average mass of an atom, taking into account the amount of each isotope present in a naturally occurring sample of an element. This type of average is called a weighted average or a weighted mean.

Question 20

How do you calculate the RAM of an element from the relative abundances of its isotopes?

Answer 20

For an element containing 2 isotopes A and B:

RAM=(% of isotope A x mass of isotope A) + (% of isotope B x mass of isotope B) / 100

Question 21

What are the elements in the Periodic Table arranged in order of?

Answer 21

They are arranged in order of atomic number, in groups and periods.

Question 22

How many electrons can the first shell/energy level hold?

Answer 22

2 electrons

Question 23

How many electrons can the second shell/energy level hold?

Answer 23

8 electrons

Question 24

How many electrons can the third shell/energy level hold?

Answer 24

A maximum of 8 electrons for the first 20 elements.

Question 25

Which shells/energy levels are filled first?

Answer 25

Lower energy levels are always filled before higher ones; the shells closest to the nucleus are filled first.

Question 26

What is the arrangement of electrons in an atom called?

Answer 26

The arrangement of electrons in an atom is called its electronic configuration.

Question 27

How do you draw diagrams of electronic configurations?

Answer 27

When we draw diagrams of electronic configurations, we draw circles to represent the shells (energy levels); dots/crosses are then drawn on the circles to represent the electrons.