Covalent bonding

Question 1

What is a covalent bond?

Answer 1

When a non metal and nonmetal share electrons rather then gaining or losing electrons. They do this because they ant to achieve a full outer shell

Question 2

What are some properties of covalent bonds? (2)

Answer 2

• forces of attractions between particles are weak.

- no charged particles are free to move through substances.

Question 3

What are some properties of covalent molecules?

Answer 3

• they are quiet strong but the intermolecular forces are quiet weak
• low boiling and melting point
• can be found in all 3 states at room temp
• non conductive

Question 4

What is a discrete molecule?

Answer 4

Each molecule is seperate and distinct from others. Diatomic molecules are composed of two of the same atoms.

Question 5

Do covalent molecules have high electronegativities?

Answer 5

Yes, , covalent molecules do have high electronegativies as they attract electrons easily as they need to gain electrons to fill their outer shell.

Question 6

Why do nonmetals share electrons?

Answer 6

When 2 nonmetals react together, they both need to gan electrons to fill their outer shell, since they cannot become negative ions, they share their outer electrons to achieve an outer shell and reach a more stable state.

Question 7

What makes hydrogen a special covalent atom?

Answer 7

It only contains one electron in its first and outer shell.

Question 8

What is another name for the electron dot diagram?

Answer 8

Lewis diagram.

Question 9

What are lone pairs and bonding pair electrons?

Answer 9

Bonding electrons: electrons that are not paired with any other electrons in the atom and are available for bonding with other atoms.
Lone pair: electrons in an atoms that are not available for bonding.

Question 10

What is a structural formula?

Answer 10

Showing how the atoms are bonded by placing a dash for each bonded pair of electrons.

Question 11

What are the three types of molecular models?

Answer 11

• ball and stick model
• space filling model
• computer generated model

Question 12

What shape do all molecules have? 3D or 2D?

Answer 12

3D

Question 13

What is a VESPR?

Answer 13

Valence shell electron pair repulsion theory. This theory states that electron pairs repel each other and take up positions as far away from one another as possible.

Question 14

What are the 4 rules for naming binary compounds?

Answer 14

1. First element is named in full.
2. Second element is names as an anion and given use prefix.
3. Number of each type of element is indicated by prefix.
4. If second element begins with a vowel the ending of the prefix (o or a) is dropped.

Question 15

What is electronegativity?

Answer 15

The electron attracting power of an element. FONCl have the highest electronegativity’s.

Question 16

What is a polar bond?

Answer 16

When a bonding electron pair is shared unequally between the nuclei of 2 bonded atoms. This occurs when atoms have elements have different electronegativy’s. The element with the higher electronegativity pulls the electrons closer to its nuclei and therefore gets a slightly negative charge as there are more electrons on its side.

Question 17

What is a non polar bond?

Answer 17

When a bonding electron pair is shared equally between the nuclei of 2 bonded atoms. This occurs when atoms have elements have similar electronegativy’s.

Question 18

What is a dipole charge?

Answer 18

A dipole charge can only occur in polar molecules. This is due to the more electronegativity element pulling the electron pair closer to its nuclei and giving the other element and itself a slight charge.

Question 19

What is a dispersion force?

Answer 19

When more electrons are found on one side of the atom than the other. This creates an instantaneous dipole because one side is more negative than the other.

Question 20

What is a hydrogen bond?

Answer 20

A hydrogen bond is when Fluorine, oxygen or nitrogen are bonded to a hydrogen atom. These highly electronegative atoms draw the electron pair closer to their nuclei and this causes hydrogens nucleus to become exposed. This forms a dipole. and it can then bond to the (FON). Its bond is so strong because hydrogens nucleus is exposed so the other atoms can come really close.

Question 21

Properties of hydrogen bonding in water?

Answer 21

• Water has a higher meting point than other substances
• Water expands upon freezing
• Ice is less dense than liquid water: molecules move further apart as they solidify to maximise hydrogen bonding.
• Ice floats on water due to being less dense then water.]

Question 22

What are the properties of molecular substances?

Answer 22

• Do not conduct electricity: atoms are neutral + no ions
• Do not conduct electricity in water if they don react with it
• If they do react with water they ionise and can conduct electricity
• Like substances can dissolve in water e.g. if polar
• Have low melting points as intermolecular forces are weak
• Are soft and easily scratched

Question 23

How to determine the boiling point of a molecule.

Answer 23

Non polar: if the molecule large, if so it has strong dispersion forces
Polar: It will have dipole forces which are stronger than dispersion. Check if there are hydrogen bonds as they are the strongest.