Unit 1 - Atomic structure and bonding

Question 1

Name the subatomic particles that are found in an atom

Answer 1

Protons

Neutrons

Electrons

Question 2

Describe subatomic particles in terms of their location, mass and charge.

Answer 2

- Protons are positive and located in the nucleus

- Neutrons are neutral and located in the nucleus

- Electrons are negative and located: around the nucleus or in the electrons shells or in energy levels.

Question 3

An atoms have a mass number of 25 and atomic number of 13, how many

protons,

neutrons

and electrons

does this atom have>

Answer 3

Protons: 13

Neutrons: 25-13 = 12 neutrons

Electrons: 13

Question 4

How many protons, neutrons and electrons are present in this atom.

What is the name of this element?

Answer 4

Protons = atomic number = 89

Neutrons = mass number - atomic number= 227 - 89 = 138

Electrons = 89 (same as number of protons in an atoms)

Name of element: Actinium

Question 5

Why an atom is always neutral?

Answer 5

Because it has the same amount of protons (oositive charges) and electrons (negative charge)

Question 6

Write the nuclide notation for the element that has 35 protons and 45 neutrons.

Answer 6

Question 7

Give an example of an element with similar chemical properties of Iodine. Explain why they have similar chemical properties.

Answer 7

Any element from group 7.

Because they are in the same group and have the same amount of electrons on their outer shell.

Question 8

What is an ion?

Answer 8

An atom that has lost or gained electrons to become stable.

Question 9

What is the name of group 1, 7 and 0/8 in the periodic table?

Answer 9

Group 1: Alkalis metals

Group 7: Halogens

Group 8/0: Noble gas

Question 10

Write the electron arrangement for an atom of carbon.

Answer 10

Carbon atom has 12 protons, so will have 12 electrons.

The electron arrangement for carbon atom is: 2,8,2

Question 11

How many electrons does Sulfur need to loose or gain to become stabe?

Answer 11

Sufur has the electron arrangement: 2,8,6

to become stable, sulfur need to gain 2 electrons, and would have the electron arrangement 2,8,8

Question 12

Write the electron arrangement of Aluminium ion.

Answer 12

Aluminium atom has the electron arrangement: 2,8,3

to become stabe and become an ion it need to loose 3 electrons, the electron arrangement for Aluminium ion is: 2,8

Question 13

How does an atom become a positive ion? For example Ca²⁺?

Answer 13

Atoms become positive ions by loosing electrons.

Ca²⁺ has lost 2 electrons.

Question 14

How does atoms become negative ions? For example N^3- ?

Answer 14

Atoms become negative ions by gaining electrons. For example N^3- has gained 3 electrons.

Question 15

Draw the electron arrangement for Sulfur ion.

Answer 15

Question 16

Give the definition of an isotope.

Answer 16

Isotopes are:

Elements with the same atomic number but different mass number

or

Elements with the same number of protons but a different number of neutrons.

Question 17

Explain what is the RAM (Relaive Atomic Mass)

Answer 17

The relative atomic mass of an element is the average mass of its atoms.

Question 18

Answer 18

Question 19

Answer 19

W and Y

Question 20

A sample of nitrogen was found to contain two isotopes.

The isotope with a mass number of 14 was present at 70% and the other with a mass of number 15 was present 30%.
What is the relative atomic mass of this sample of nitrogen?

Answer 20

(14x70)+(15x30) / 100 = 14.3

Your result for the RAM should always be between the different mass number, if you have a higher number, you probably forgot to divide by 100, if your number is smaller, you probably divided by 100 too many times.

Question 21

Describe how covalenent bonds are formed.

Answer 21

By sharing a pair of electrons.

Question 22

What type of atoms can be found in covalent bond?

Answer 22

non-metals with non-metals

Question 23

Draw a dot and cross diagram for water.

Answer 23

Question 24

Draw a dot and cross diagram for N₂

Answer 24

Question 25

Draw a dot and cross diagram for CH₄

Answer 25

Question 26

What is the shape of a diatomic molecule?

Answer 26

linear

Question 27

What is the shape of a molecule of water?

Answer 27

angular

Question 28

What is the shape of NH₃

Answer 28

Trigonal pyramidal

Question 29

What is the shape of CH₄

Answer 29

tetrahedral

Question 30

What are the 2 type of covalent structure?

Answer 30

Covalent molecular (like Water) Covalent netwrok (like diamond)

Question 31

What are the difference in properties between covalent molecular and covalent network?

Answer 31

Covalent compound (both molecular and network) do NOT conduct electricity. However, **covalent molecular** structure have **low** **melting and boiling point.** **Covalent network** have **high** **melting and boiling point.**

Question 32

Describe how ionic bond are form. Use Magnesium Fluoride to illustrate your explaination.

Answer 32

Ionic compounds are formed by transfering electrons. Metals elements give away their outer electron(s) and non-metals accept these electron(s). For example, in magnesium fluoride (MgF₂), magnesium lose 2 electrons and become Mg²⁺ and two fluorine atom gained an electron each and become F^-. Mg²⁺ and 2F^- are attracted together by electrostatic forces.

Question 33

what type of atoms can formed ionic bonding?

Answer 33

**Metals + non-metals.** ## Footnote Ions are formed when atoms lose or gain electrons to obtain the stable electron arrangement of a noble gas. In general, metal atoms lose electrons forming positive ions and non-metal atoms gain electrons forming negative ions. Ion-electron equations can be written to show the formation of ions through loss or gain of electrons. Ionic bonds are the electrostatic attraction between positive and negative ions

Question 34

Describe the properties of ionic compounds (melting point, boiling point and electrical conductivity)

Answer 34

* Ionic compounds have high melting point and boiling point * Ionic compounds conduct electricity when molten or in solution but they **DO NOT** conduct electricity when solid.

Question 35

What type of bonding is represented in the diagram?

Answer 35

Metallic bonding

Question 36

Describe how metallic bonding are formed and explain why they conduct electricity.

Answer 36

* Metallic bonding is the electrostatic force of attraction between positively charged ions and delocalised electrons. * Metallic elements are conductors of electricity because they contain **delocalised electrons** that are free to move

Question 37

What type of bonding is represented in the diagram?

Answer 37

Ionic bonding

Question 38

Explain why ionic bonding conduct electricity when they are in solution.

Answer 38

Become the **IONS** are free to move

Question 39

What type of bonding is represented in the diagram?

Answer 39

Covalent molecular

Question 40

What type of bonding is represented in the diagram?

Answer 40

Covalent network