🧪 | Unit 3 | Structure & Bonding

Question 1

Properties of metals

Answer 1

∘ lustrous
∘ high m.p.
∘ high densities
∘ malleable + ductile
∘ conduct electricity + heat
∘ lose electrons - form cations
∘ form basic oxides

Question 2

Properties of non-metals

Answer 2

∘ non-reflective
∘ low m.p.
∘ low densities
∘ brittle, delicate in solid state
∘ do not conduct electricity or conduct heat

∘ gain electrons - form anions
∘ form acidic oxides
∘ non-metals bond to form covalent compounds

Question 3

Lattice

Answer 3

A regular arrangement of alternating positive and negative ions.

Question 4

What is the proton number?

Answer 4

The proton number is the number of protons in the nucleus of an atom.

Question 5

What is the nucleon number?

Answer 5

The nucleon number is the total number of protons and neutrons in the nucleus of the atom.

Question 6

Properties of covalent compounds

Answer 6

• have low m.p. and b.p.
• liquids and gases at room temperature
• volatile
• not water-soluble
• can’t conduct electricity

Question 7

Properties of ionic compounds

Answer 7

• high m.p. and b.p.
• solid at room temperature
• not volatile
• water-soluble
• conduct electricity in molten state or in aqueous solution
• brittle

Question 8

How are covalent compounds formed?

Answer 8

Covalent compounds are formed when electrons are shared between non-metal atoms to have full valence shells.

Question 9

How are ionic compounds formed?

Answer 9

Ionic compounds are formed when electrons are transferred from one atom to another to have a full valence shell.

Question 10

What are ionic bonds?

Answer 10

Ionic bonds are electrostatic forces of attraction between opposite charges.

Question 11

What is an ion?

Answer 11

An ion is an electrically charged atom formed by the loss or gain of electrons.

Question 12

What is an alloy?

Answer 12

An alloy is a mixture of a metal with other elements.

Question 13

Define isotope

Answer 13

Isotopes are atoms of the same element that have the same proton number but different nucleon numbers.

Question 14

Why do isotopes still have the same properties?

Answer 14

Isotopes still have the same properties because they have the same number of valence electrons.

Question 15

What is an atom?

Answer 15

An atom is the smallest particle of a substance that can exist.

Question 16

What is an element?

Answer 16

An element is a substance that is made up of the same type of atom and cannot be split into anything further.

Question 17

What is a compound?

Answer 17

A compound is a pure substance made up of two or more elements that are chemically bonded.

Question 18

What is a mixture?

Answer 18

A mixture is a combination of 2 or more substances that are not chemically bonded.

Question 19

What is a pure substance?

Answer 19

A substance that contains only one element is a pure substance.

Question 20

What is a molecule?

Answer 20

Two or more atoms bonded together is a molecule.

Can be same or different elements.

Question 21

Structure of an atom

Answer 21

• electron shells with electrons

- nucleus: protons and neutrons

Question 22

Mass of a proton

Answer 22

1 amu

Question 23

Mass of a neutron

Answer 23

1 amu

Question 24

Mass of an electron

Answer 24

1/1836 amu

Question 25

Charge of a proton

Answer 25

+1

Question 26

Charge of a neutron

Answer 26

No charge

Question 27

Charge of an electron

Answer 27

-1

Question 28

What is | atomic number?

Answer 28

The number of protons in the nucleus of an atom is the atomic number.

Question 29

What is | mass number?

Answer 29

The total number of neutrons and protons in the nucleus of an atom is the mass number.

Question 30

What is an isotope?

Answer 30

An isotope is a atom of the same element with the same number of protons but different number of neutrons.

Question 31

How to draw an ion?

Answer 31

With the ions of each element in those box-brackets, include the charge.

Question 32

Ionic bonds are formed between what types of elements?

Answer 32

Ionic bonds are formed between metallic and non-metallic elements

Question 33

Properties of diamond

Answer 33

- giant tetrahedral structure (each C atom bonded to 4 other C) - many strong covalent bonds that require a lot of energy to break - does not conduct electricity - has a very high melting point - is extremely hard and dense

Question 34

Allotrope

Answer 34

Different forms of the same element

Question 35

Properties of graphite

Answer 35

∘ each C atom is bonded to 3 other C atoms ∘ has a slightly lower m.p. than diamond ∘ many strong covalent bonds that require a lot of energy to break ∘ slippery ∘ soft ∘ layers with weak intermolecular forces between the electrons ∘ can conduct electricity: there is a delocalized electron for each carbon atom

Question 36

Properties of silicon dioxide

Answer 36

∘ each Si atom bonds to 4 oxygen atoms ∘ each oxygen atom bonds to 2 Si atoms ∘ giant, tetrahedral structure ∘ very hard ∘ high density and boiling point ∘ insoluble in water ∘ can't conduct electricity

Question 37

What is a covalent bond?

Answer 37

The electrostatic attraction between a positive nucleus and a shared pair of electrons

Question 38

Simple molecular substances have low m.p. | Why?

Answer 38

They have weak intermolecular forces which are easy to break.

Question 39

What is metallic bonding?

Answer 39

Metallic bonding is a lattice of positive ions in a "sea" of electrons.

Question 40

Why can metals conduct electricity?

Answer 40

The sea of electrons are delocalized electrons, meaning that they are able to move and carry charge.

Question 41

Why do metals have high m.p.?

Answer 41

They have strong metallic bonds.

Question 42

What is a metallic bond?

Answer 42

The electrostatic attraction between a positive metal ion and the sea of delocalized electrons.

Question 43

Why can metals conduct heat?

Answer 43

The delocalized electrons can pass on thermal energy.

Question 44

Why are metals malleable and ductile?

Answer 44

The layers of positive ions can slide over each other.

Question 45

Why are alloys harder than pure metals?

Answer 45

Alloys are of different metals, which means the positive ions are in different sizes. This doesn't allow the layers of positive ions to slide over each other.

Question 46

Why are ionic compounds water-soluble?

Answer 46

Both ionic compounds and water are polar.

Question 47

Why are ionic compounds brittle?

Answer 47

When the ionic compound is hit, the layers of ions in the lattice slide over each other, causing ions of the same charge to slide next to each other and repel.