Properties of Matter - Bonding

Question 1

How does electronegativity determine the ionic or covalent nature of bonds between atoms?

Answer 1

Low electronegativity + Low electronegativity = metallic bond

Low electronegativity + High electronegativity = ionic bond

High electronegativity + High electronegativity = covalent bonding

Question 2

Explain the metallic bond process

Answer 2

Because metallic elements possess low electronegativities, cations are formed. The cations come together, and the loosely held valence electrons form a ‘sea of delocalised electrons’, in which the valence electrons don’t belong to any specific atom. The strong electrostatic attraction between metal cations and surrounding, free mobile electrons is what creates the metallic bond and the sea of delocalised electrons

Question 3

What is a sea of delocalised electrons?

Answer 3

Basically, when a metallic element loses its valence electrons during a metallic bond because they have low electronegativity, the valence electrons float around near the cations as they are attracted to them (opposites attract), however they aren’t strong enough to fully bring the electron into the outer shells of some atoms

Question 4

What is a sea of delocalised electrons?

Answer 4

Basically, when a metallic element loses its valence electrons during a metallic bond because they have low electronegativity, the valence electrons float around near the cations as they are attracted to them (opposites attract), however they aren’t strong enough to fully bring the electron into the outer shells of some atoms

Question 5

What is the octet rule?

Answer 5

The octet rule states that atoms want to gain, lose or share electrons to achieve noble gas configuration, which is basically a full outer shell of 8 electrons.

Question 6

What are the different types of molecular forces?

Answer 6

Intermolecular forces and Intramolecular forces

Question 7

What are intermolecular forces?

Answer 7

Intermolecular forces is an interaction that can be found between molecules. They are also known as weak or secondary bonds because they are weaker at attraction than intramolecular forces. This is because the power of attraction/repulsion between atoms is stronger as opposed to attraction/repulsion between molecules

Question 8

What are intramolecular forces?

Answer 8

Intramolecular forces are strong attractions between the atoms of a molecule, this is because the electrons of the atoms share or give their electrons, which creates a bond which is hard to break. They are also known as primary bonds / chemical bonds.

Question 9

What are allotropes?

Answer 9

Allotropes refer to the different physical structures that an element can take

Question 10

What elements are some examples of allotropes?

Answer 10

Carbon - Can take the form of diamonds and graphite
Phosphorous - White, Red, Black Phosphorous

Question 11

What are the two different types of covalent bonds?

Answer 11

Polar and Non-polar covalent bonds

Question 12

What are polar covalent bonds?

Answer 12

Polar covalent bonds basically mean when shared pairs of electrons spend more time near a certain atom than another. This results in a slightly more positive and negative atom. (The electron sharing is UNEQUAL)

An example of this would be HCl.

Question 13

How do polar covalent bonds form?

Answer 13

They are formed when a covalent bond is formed. Because one atom is more electronegative than the other, that means, the electrons are more attracted to that certain atom. hence why the electrons might spend more time near the certain atom and less time with the other atom. This results in a slightly more negative charge on the ‘certain atom’ and a slightly more positive charge on the other atom.

Question 14

What is the symbol for a ‘little bit’ (particularly significant for polar covalent bonds)

Answer 14

δ (delta), followed by a small minus or plus sign next to it indicating the charge

Question 15

What are non-polar covalent bonds?

Answer 15

Basically the opposite of polar covalent bonds in the fact that there is an EQUAL sharing of electrons between the two atoms.

An example of this would be H2 gas

Question 16

How do non-polar covalent bonds form?

Answer 16

They are formed when there is a covalent bond between two same elements or a covalent bond between two elements of the same (or really similar) electronegativities. This means that there is no certain atom that electrons are more likely to be attracted to, but instead remain equally shared

Question 17

What is an ionic bond?

Answer 17

An ionic bond is the outright transfer of electrons from one atom to another. It consists of electrostatic attraction between the positive and negative ions. An ionic compound formula specifies the ratio of ions present not the number of ions. In this bond, metal atoms lose valence electrons and become positively charged, whereas non-metal atoms gain valence electrons and become negatively charged

Question 18

How does ionic bonding work?

Answer 18

The metal atoms lose their valence electrons to the non-metal atoms. This results in the metal atom being a cation and the non-metal atom being an anion.

Question 19

What is an ionic lattice?

Answer 19

An ionic lattice is where the ions of a solid ionic compound aren’t randomly arranged, but instead have a regular, set, repeating order in which each ion has a set position in the lattice (the orderly arrangement of ions). The lattice is formed because the ions attract each other and form a regular pattern with oppositely charged ions next to each other.

Question 20

What is an ionic network compound?

Answer 20

Basically another word for ionic lattice and consists of cations and anions occupying fixed positions in a crystal lattice

Question 21

What does the nature of the ionic network compound tell us about the physical properties? (transparency, MP and BP, thermal and electrical conductivity, solubility, malleability)

Answer 21

Mostly transparent (electrons aren’t moving from atom to atom like covalent, and don’t interact with light)

High Melting and Boiling Points (high electrostatic forces, thus more energy required to break all the bonds, thus high MP, BP)

Low Thermal Conductivity (ions in fixed positions)

No electrical conductivity as a solid, but high in a liquid (ions free to move in a liquid but not as a solid)

Mostly soluble in water (hydration occurs, which breaks the crystal and the ions are free to move around (H and O atoms connect with the opposite charges and release them))

Brittle (When applying force, it results in one layer of ions to shift relative to its neighbour. However, when that happens, it brings ions of the same charge next to each other. The repulsive forces between like-charged ions cause the crystal to shatter.)

Question 22

How do you determine whether or not a compound is electrical or thermally conductive?

Answer 22

Basically determined by whether or not the ions or free to move or not. If they are, they easily conduct, if not they are insulators because they are in fixed positions and don’t spread the energy everywhere else. Opposite, when they are free (I think)

Question 23

How are covalent bonds formed?

Answer 23

When two atoms share electrons

Question 24

What are double and triple bonds? (covalent)

Answer 24

Sharing of two electrons of each atom (4 shared altogether), and triple bonds are sharing of three electrons of each atom (6 shared altogether)

Question 25

What are covalent molecular substances?

(need to double check)

Answer 25

Otherwise known as discrete covalent molecules, they are a type of covalent substance, and they basically mean that they are made up of simple discrete covalent molecules, these molecules contain a fixed number of atoms joined by covalent bonds. In other words, these substances are separate and distinct particles which can move independently of each other, but are still considered a covalent bond, and they are held together by weak intermolecular forces (because of the covalent bonds between the molecules).

Question 26

What are the physical characteristics of covalent molecular substances?()

Answer 26

Low melting and boiling point
Soft and Flexible
Does not conduct electricity
Mainly not soluble in water

Question 27

What are covalent network substances?

Answer 27

Covalent network substances are made of continuous, repeating, three-dimensional arrangements of covalently bonded atoms

Question 28

What is a covalent network lattice?

Answer 28

They are basically giant covalent substances which contain many atoms joined by covalent bonds. These covalent bonds are strong.

Question 29

What are covalent network solids?

Answer 29

This is where the covalent bonding extends indefinitely throughout the whole crystal. Some examples of covalent network solids include diamonds and silica(sand)

Question 30

What are characteristics of covalent lattices?

Answer 30

High melting points, boiling points (strong intramolecular covalent bonds make it harder to melt/boil)

Not conductive of electricity (no ions and no free electrons to conduct)

Insoluble in water

Question 31

Can you use lines for electron dot structures?

Answer 31

No

Question 32

What are electron dot structures also known as?

Answer 32

Lewis Dot Structures

Question 33

What is a Lewis Dot Structure?

Answer 33

It is basically a simplified version of the valence electrons of an atom, and it also shows how the atoms of a molecule are bonded. It consists of 8 ‘dots’ (electrons), 2 on each side of the element symbol which is in the middle

Need to practice

Question 34

What symbol is used to represent a valence electron in an atom using the Lewis Dot Structure?

Answer 34

A dot

Question 35

Does order matter for Lewis Dot Structure?

Answer 35

No it doesn’t, but we have to make sure that we draw the dots so that they aren’t paired up if possible.

Question 36

What are the steps of drawing a Lewis Dot Structure?

Answer 36

Have the element in the middle, and then use a dot to represent the amount of valence electrons the atom has, and then space it around the symbol.

Question 37

How do you draw covalent Lewis Dot Structures?

Answer 37

Have the two elements on the left side (not connected), with valence electrons depicted and a plus sign between the two elements. After that, put an arrow pointing to the right with the elements on the right, and the electrons being shared having a circle around them. (Same rule applies with double and triple bonds)

Need to practice irl

Question 38

How do you draw ionic Lewis Dot Structures?

Answer 38

Have the two elements on the left side (not connected), with valence electrons depicted and a plus sign between the two elements. After that, put an arrow pointing to the right with the two separate elements with square brackets around them. The cation should have no dots around it, whereas the anion should have a full 8 electrons. After that, put the charge of the cation and anion outside the square brackets.

Need to practice irl

Question 39

What is the VESPR theory?

Answer 39

VESPR stands for Valency Electron Shell Pair Repulsion. It states that:

The bonding pair of electrons and lone pairs repel each other and thus adopt the 3D geometry that maximises the distance between negatively charged electron pairs

The number of repelling electron pairs around a central atom affects the molecular shape

Question 40

What are considered VESPR groups?

Answer 40

A bonding pair

Unshared lone pair

Double or triple bond

Question 41

What are the different ways of representing molecular shapes?

Answer 41

Space filling models (when the atoms are like basically merged into each other)
Ball and Stick models (the school things)
Perspective drawings (a 2D drawing which shows the different bonds with different shapes i think)

Question 42

What are the five main shapes and the degrees between the electrons?

Answer 42

Linear - 180 degrees
Trigonal Planar and Bent - 120 degrees
Tetrahedral - 109.5 degrees
Trigonal pyramidal - 107 degrees?

Look at pics of them

Question 43

What are dipoles?

Answer 43

Dipoles refer to a pair of equal but opposite charges separated in space such as the H - Cl molecule

Question 44

How are dipoles represented when drawn?

Answer 44

Dipoles are indicated by an arrow with a crossbar, where the head of the arrow points to the more negatively charged end of the dipole (typically the more electronegative atom)

(look at pic) –+—–> (kind of like that)

Question 45

What do the shapes of the molecule say about the potential polar bonds?

Answer 45

Generally:
Asymmetrical - Polar
Symmetrical - Non polar

Question 46

What is the effect of polar bonds on MP and BP

Answer 46

Being polar affects the intermolecular forces and therefore the MP and BP, and thus they increase as there are stronger intermolecular forces

Question 47

What are dipole-dipole interactions?

Answer 47

This basically occurs when polar molecules line up so that the negative end of one of the molecules attracts the positive end of another molecule, thus the electrostatic attraction holds the molecules together more strongly than non-polar molecules. These electrostatic attractions are called dipole-dipole interactions

(look back at ppt pg 27 - 4.1b for a good question)

Question 48

What are dispersion forces?

Answer 48

This is the force that is present in every substance, even when other intermolecular forces are acting. These forces arise due to random movements of electrons around atoms and molecules

The force which is released due to the temporary dipole is what causes a dispersion force. A dispersion force is extremely weak. The size of dispersion forces increase with the number of electrons

The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.

(double check what it is exactly)

Question 49

What is a temporary dipole?

Answer 49

These exist in non-polar covalent bonds, and is when equally shared electrons between the two bonded atoms of a molecule spontaneously distribute unevenly with more electrons in one atom than another. This is because the electrons are in constant movement around the nucleus, and thus the electrons spontaneously concentrate in one atom, causing the atom to be more negative than the other.

Question 50

What is hydrogen bonding?

Answer 50

Hydrogen bonding is stronger types of Polar interactions. It refers to a electrostatic attraction which is the result of a H (hydrogen) atom bonded to F (Fluorine), O (Oxygen), N (Nitrogen) becoming attached to another one of those atoms in another molecule. E.g. H2O and NH3 or H2O and H3N (?)

Question 51

Why are covalent molecular substances soft?

Answer 51

Because covalent molecular substances are made up of discrete covalent molecules. This means that the molecules are free to move past each other thus resulting in them being soft and flexible

Question 52

Why are bonds other than covalent molecular substances hard?

Answer 52

Because it is hard to remove the ions from one another in covalent network, ionic and metallic.

Question 53

Why can metallic and molten ionic substances conduct electricity while covalent substances do not?

Answer 53

Because ions are free to move from place to place. Electricity needs ions to be able to touch to conduct electricity. Also solid ionic substances can’t because they are in a lattice and the ions are in fixed places (not free), however once they become molten they can conduct electricity

Question 54

Why are covalent molecular substances, metallic bonds and Ionic bonds unable to be soluble in water?

Answer 54

?

Question 55

What are the characteristics of ionic bonds? Why (3)

Answer 55

High Melting and Boiling Points (a lot of energy is required to overcome the attraction between positive and negative ions

Hard and Brittle (Hard because the cations and anions are heavily attracted towards each other and difficult to separate, brittle because when an ionic crystal shatters, like charges or brought together which causes it to shatter (like charges repel))

Conduct electricity when molten (the delocalised (when molten) ions are free to move around and conduct electrons whereas in a solid, the ions are bound tightly to each other)

Question 56

What are the characteristics of metallic bonds? Why (4)

Answer 56

Metallic bonds are good electrical conductors (Electrons are free to move in the sea of delocalised electrons, and can carry a charge)

Metallic bonds are good thermal conductors (free electrons are able to transfer energy away from the heat source and also because vibrations of atoms (phonons) move through a solid metal as a wave.)

Soft and flexible (malleable) (because the binding between the metals are non-directional and electrons are free to move around, thus when hammered it doesn’t force like charges together which shatters)

High Melting and Boiling points (Because metallic bonds typically come in the form of giant lattice structures, there is more electrostatic forces required to break them)

Question 57

What are some examples of covalent network bonds? (4)

Answer 57

Diamond, graphite, silicon dioxide, quartz