Chapter 3 - Covalent Substances

Question 1

Allotrope

Answer 1

Different structural arrangements of the same element. For example, diamond and graphite are both made of carbon, but diamond has a covalent network lattice, whereas graphite has a covalent layer lattice.

Question 2

Amorphous

Answer 2

A substance that does not have a clearly defined structure. E.g. amorphous carbon.

Question 3

Asymmetrical Molecule

Answer 3

A molecule that is not symmetrical, meaning that it will be polar if it contains polar bonds. For example: trigonal pyramid and planar shapes.

Question 4

Covalent Bond

Answer 4

A strong chemical bond between non-metal atoms, created through the sharing of valence electrons. Results in a molecule.

Question 5

Covalent Lattice

Answer 5

A regular arrangement of atoms joined by covalent bonds.

Question 6

Covalent Layer Lattice

Answer 6

A lattice (such as graphite) made up of two dimensional layers of atoms, held together by weak dispersion forces. Each atom is bonded to three other atoms. Lustrous, conducts electricity, acts as a lubricant and has a high sublimation point.

Question 7

Covalent Network Lattice

Answer 7

A covalent lattice with each atom bonded to four other atoms, such as in diamond; hard and have high melting points.

Question 8

Diamond

Answer 8

An allotrope of carbon formed by a covalent network lattice, with each carbon atom bonded to four other carbon atoms. Is hard, translucent and brittle, with a high melting point. Does not conduct electricity.

Question 9

Diatomic Molecule

Answer 9

A linear molecule that is only made up of two atoms, such as HCl.

Question 10

Dipole

Answer 10

A pair of oppositely charged regions around a molecule, represented by the Greek letter δ (delta).

Question 11

Dipole-Dipole Attraction

Answer 11

An intermolecular force between polar molecules; the electrostatic attraction between the positive and negative dipoles of two molecules.

Question 12

Dispersion Forces

Answer 12

A weak intermolecular force caused by the creation of an instantaneous dipole.

Question 13

Double Covalent Bond

Answer 13

A covalent bond in which two pairs of electrons are shared, such as in oxygen. Forms 3 electron domains around each atom.

Question 14

Electron Domain

Answer 14

A region in which a lone pair or bonding electrons could be found. Non-metals have 4 electron domains in their outer shell.

Question 15

Graphite

Answer 15

An allotrope of carbon formed by a covalent layer lattice, with each carbon atom bonded to three other carbon atoms. Is lustrous with a high melting point, along with having lubricant properties. Does conduct electricity.

Question 16

Hydrogen Bond

Answer 16

An intermolecular force between hydrogen and either fluorine, oxygen or nitrogen (FON). The strongest of the intermolecular forces.

Question 17

Instantaneous Dipole (Temporary Dipole)

Answer 17

The sudden or random creation of a dipole in a non-polar molecule, due to the uneven distribution of electrons.

Question 18

Intermolecular Force

Answer 18

The weak forces between molecules, such as dispersion, dipole-dipole attraction, or hydrogen bonding.

Question 19

Intramolecular Bond

Answer 19

The strong covalent bonds within molecules.

Question 20

Lewis Structure

Answer 20

A diagram consisting of dots or crosses, which illustrates the covalent bonds in a molecule.

Question 21

Molecule

Answer 21

A group of two or more atoms chemically bound together in a discreet structure. Note: not the same as a lattice!

Question 22

Non-Bonding Electrons (Lone Pairs)

Answer 22

An electron domain that has been filled by two electrons, meaning that it is (usually) unable to form covalent bonds.

Question 23

Non-Polar

Answer 23

A molecule that does not have a polar charge, due to electronegativities of its atoms being the same, or it having a symmetrical shape.

Question 24

Polar

Answer 24

A molecule that has a dipole and therefore a slight electrical charge, due to its atoms having a difference in electronegativity up to 1.7.

Question 25

Polarity

Answer 25

The strength of the electrical charge in a polar molecule. Atoms with greater differences in electronegativity will have greater polarity.

Question 26

Polyatomic Molecule

Answer 26

A molecule made up of more than two atoms.

Question 27

Trigonal Pyramidal (Molecule)

Answer 27

A molecular shape formed by three bonding pairs and one lone pair. For example: ammonia (NH3). Polar.

Question 28

Sublimation Point

Answer 28

The temperature at which a solid is able to transition directly to a gas, without first becoming a liquid.

Question 29

Single Covalent Bond

Answer 29

A covalent bond in which one pair of electrons are shared, such as in chlorine. Forms 4 electron domains around each atom.

Question 30

Symmetrical Molecule

Answer 30

A molecule with equal shape, meaning that it will not become polar, even if it has polar bonds. For example: tetrahedral shapes.

Question 31

Tetrahedral

Answer 31

A molecular shape formed by four bonding electrons, consisting of four branches extending off of a central point. Not polar.

Question 32

Trigonal Planar (Molecule)

Answer 32

A molecular shape formed by two single bonds and one double bond (a flat pyramid). Polar.

Question 33

Triple Covalent Bond

Answer 33

A covalent bond in which three pairs of electrons are shared, such as in nitrogen. Forms 2 electron domains around each atom.

Question 34

VSEPR Theory

Answer 34

Valence Shell Electron Pair Repulsion theory; an idea stating that electrons in their valence shell repel, and therefore will spread out to reduce repulsion.

Question 35

Covalent Bonding

Answer 35

Bonding between non-metal atoms, through the sharing of electrons.

Question 36

Structural Formula

Answer 36

A diagram consisting of lines, which illustrates the covalent bonds in a molecule.

Question 37

Induced Dipole

Answer 37

A temporary dipole in an atom, caused by an instantaneous dipole attracting or repelling nearby electrons.