Atoms, Ions and Ionic Compounds

Question 1

What is an element?

Answer 1

It is a pure substance made up of only one type of atom only.

Question 2

What is an atom?

Answer 2

An atom is the building block of all matter containing protons, neutrons and electrons.

Question 3

What does the atomic number of an element on the periodic table tell you about that element’s atom?

Answer 3

How many protons there are in the nucleus of that element’s atom and electrons there are in the shell(s) surrounding the nucleus

Question 4

What does the mass number of an element on the periodic table tell you about that element’s atom?

Answer 4

How many proton and neutrons there are in total in the nucleus of that element’s atom

Question 5

What are the maximum number of electrons in each of the first three shells in an atom?

Answer 5

1st shell = 2, 2nd and 3rd shells = 8

Question 6

Describe the electron arrangement of potassium (atomic number = 19)

Answer 6

2,8,8,1

Question 7

Describe the electron arrangement of silicon (atomic number = 14)

Answer 7

2,8,4

Question 8

In the periodic table, what does the group (column) an element is found in tell you about that element’s atom?

Answer 8

How many electrons there are in its outer/valence shell

Question 9

In the periodic table, what does the period (row) an element is found in tell you about that element’s atom?

Answer 9

How many electron shells the element’s atom has

Question 10

Describe the electron arrangement of an atom that is found in the 3rd period and 2nd group

Answer 10

It has 3 electron shells and two electrons in its outer shell. Therefore is has the electron arrangement 2,8,2

Question 11

Describe the electron arrangement of an atom that is found in the 2nd period and 17th group

Answer 11

It has 2 electron shells and 7 electrons in its outer shell. Therefore it has the electron arrangement 2,7

Question 12

Define an ion

Answer 12

It is an atom that has gained or lost electrons in order to form a full outer/valence shell and be chemically unreactive/stable.

Question 13

Elements from what groups are highly reactive and explain why?

Answer 13

Group 1 and group 17 are because group 1 elements only have to lose one eletcron to have a full outer shell and group 17 elements only have to gain one electron in order to have a full outer shell

Question 14

Do metals gain or lose electrons to form ions?

Answer 14

Lose electrons

Question 15

Why are ions charged but atoms are not?

Answer 15

Atoms have the same number of positive protons and negative electrons. Ions have either gained or lost electrons and so there are different numbers of positive protons and negative electrons.

Question 16

Explain why sodium has a +1 charge

Answer 16

A sodium ion formed from a sodium atom by losing one electron in order to have a full valence shell and be unreactive. Therefore it has one more positive proton than negative electron.

Question 17

Explain why oxygen has a -2 charge

Answer 17

An oxide ion formed from an oxygen atom by gaining two electrons in order to have a full valence shell and be unreactive. Therefore it has two more negative electrons that positive protons.

Question 18

What is an ionic compound?

Answer 18

An ionic compound is formed when a positive ion and a negative ion are joined together due to the differences in electrostatic charge.

Question 19

What charge do ionic compounds have?

Answer 19

All ionic compounds are neutral

Question 20

What is the ratio of ions in NaCl?

Answer 20

One sodium ion to one chloride ion.

Question 21

What does sodium chloride have formula NaCl in terms of electron arrangement?

Answer 21

When a sodium atom formed an ion it lost one electron from its valence shell. Chlorine needed one electron to fill its outer shell to form a chloride ion. Therefore the ratio of ions in NaCl is one sodium ion to one chloride ion.

Question 22

What does sodium chloride have formula NaCl in terms of the ions?

Answer 22

A sodium ion has a 1+ charge and a chloride ion has a 1- charge. Because all ionic compounds are neutral, it only takes one sodium ion to cancel the charge of the one chloride ion.