Atomic Structure and Bonding

Question 1

Periods

Answer 1

Horizontal rows on the periodic tabl. All elements in the same period have the same number of electron shells.

Question 2

Groups

Answer 2

Vertical columns on the periodic table. All elements in the same group have similar chemical properties and the same numbe rof valence electrons.

Question 3

Mass of a Proton, Neutron and Electron.

Answer 3

1, 1, 0.0005 (negligable)

Question 4

Charge of a Proton, Neutron and Electron

Answer 4

1+, 0, 1-

Question 5

What is the top number of an element on the periodic table?
Eg: 3
Li
lithium
7

Answer 5

Atomic number.
(also number of protons/electrons in the atom)

Question 6

What is the bottom number of an element on the periodic table?
Eg: 3
Li
lithium
7

Answer 6

Atomoic mass number.
(also number of protons + neutrons)

Question 7

Octet Rule

Answer 7

The tendency of atoms to prefer to have 8 electrons in the valence shell. Rule: [2,8,8,2] or [2,8,18,18,8,2]

Question 8

Halogen

Answer 8

All elements in group 7.

Question 9

Alkali metals

Answer 9

All elements in group 1.

Question 10

Noble Gases

Answer 10

All elements in group 8. Their valence shells are full so they cannot become bonded.

Question 11

Ionic Bond

Answer 11

The electrostatic force of attraction between oppositely charged ions (cations and anions / metal and non-metal).

Question 12

Lattice

Answer 12

A regular repeated 3-D arrangement

Question 13

Giant

Answer 13

Undefined number of particles (eg: ions) in the lattice. Simplest whole number ratio.

Question 14

Polyatomic ion

Answer 14

A chemical ion composed of 2 or more atoms covalently bonded. (eg: SO4)

Question 15

Common polyatomic ions (names AND formulas)

Answer 15

Carbonate: CO3 (2-)
Sulfate: SO4 (2-)
Hydroxide: OH (-)
Nitrate: NO3 (-)
Phosphate: PO4 (3-)
Hydrogen Carbonate: HCO3 (-)
Ammonium: NH4 (+)
(only positively charged polyatomic ion)

Question 16

Properties of ionic compounds

Answer 16

• High melting and boiling point
• Hard
• Brittle
• Often soluble in water
• Doesn’t conduct electricity as a solid
• Can conduct electricity when molten or dissolved

Question 17

How do ions have high melting and boiling points?

Answer 17

The strong electrostatic forces of attraction between the ions require a lot of heat energy to break.

Question 18

How are ions ‘mostly soluble in water’?

Answer 18

If an ionic compound is soluble, water molecules are able to break the electrostatic force of attraction between the ions.

Question 19

Describe conductivity in solid and liquid ions.

Answer 19

Ions in a solid ionic compound are not free to move and therefore cannot conduct electricity.
Whereas in a liquid/solution, ions move past eachother and charge can flow, inducing a current.

Question 20

How are ions ‘brittle’?

Answer 20

When a force is applied, the ions in the lattice shift so that like charges repel and the lattice breaks.

Question 21

How are ions ‘hard’?

Answer 21

Ionic compounds have strong electrostatic forces of attractions between oppositely charged ions.

Question 22

Flame tests

Answer 22

Flame tests are used to detect the presence of a metal ion.
Lithium (Li+) = red flame
Sodium (Na+) = intense yellow/orange flame
Potassium (K+) = purple/lilac/violet flame
Calcium (Ca 2+) = brick red flame

Question 23

Ion Test - Ammonium (NH4 +)

Answer 23

1. add dilute sodium hydroxide solution
2. gently heat
3. if NH4 + is present: choking smell produced, fumes turn damp red litmus paper or damp universal indicator from red to blue

Question 24

Ion Test - Carbonate (CO3 2-)

Answer 24

1. add dilute hydrochloric acid
2. bubble gas through limewater
3. if CO3 2- is present, limewater turns cloudy

Question 25

Ion Test - Sulfate (SO4 2-)

Answer 25

1. add dilute hydrochloric acid 2. add a few drops of barium chloride solution 3. if SO4 2- is present, a white precipitate forms

Question 26

Ion Test - Hallide ions Chloride ions (Cl-) Bromide ions (Br-) Iodide ions (I-)

Answer 26

1. add dilute nitric acid 2. then add a few drops of silver nitrate solution 3. if Cl- is present, a white precipitate forms if Br- is present, a cream precipitate forms if I- is present, a yellow precipitate forms

Question 27

General properties of metals

Answer 27

- High melting and boiling point - Good conductors of heat - Hard - High density - Malleable - Ductile - Sonorous - Lustrous (exceptions: Sodium is less hard and can be cut with a knife, Mercury has a low melting and boiling point and is liquid at room temp)

Question 28

Structure/bonding of metals

Answer 28

Metal cations are attracted to the sea of delocalised electrons. This electrostatic attraction is metallic bonding. The atoms in a pure metal are in tightly packed layers, which forms a giant metallic lattice.

Question 29

How are metals able to conduct electricity?

Answer 29

Delocalised electrons can move through the structure and carry charge.

Question 30

How are metals malleable?

Answer 30

The arrangement of ions can change but the attraction between cations and delocalised electrons isn't broken.

Question 31

How are metals able to conduct heat?

Answer 31

Delocalised valence electrons can move faster and pass on energy quickly. The lattice of atoms transmits energy efficiently as the cations vibrate and bump into other cations.

Question 32

How do metals have high melting and boiling points?

Answer 32

The electrostatic force of attractions between cations and delocalised valence electrons are strong and it requires a lot of heat energy to break them.

Question 33

Alloys

Answer 33

A mixture composed of 2 or more elements, at least one of which is a metal. Alloys are generally harder, less malleable stronger and poorer conductors than pure metals because the arrangement of ions is disturbed. Eg: Stainless steel, bronze and brass.

Question 34

Covalent bonding

Answer 34

A chemical bond that involves the sharing of electron pairs between atoms. Only involves valence electrons and is usually between non-metals. These bonds are very strong and form simple molecular structures.

Question 35

Properties of simple molecular structures

Answer 35

- low melting and boiling points - can't conduct electricity in any form

Question 36

How do simple molecular structures have low melting and boiling points?

Answer 36

There are intERmolecular forces between simple molecules which are weaker than the strong covalent bonds. When simple molecular substances melt or boil, its the weak intermolecular forces that are overcome - covalent bonds are not broken.

Question 37

How are simple molecular strustures not able to conduct electricity?

Answer 37

Simple molecules have no overall charge or charged particles that can seperate so they cannot conduct electricity.

Question 38

Polarity of simple molecular structures

Answer 38

Negative electrons are held in their shells by the attraction of the positive protons in the nucleus (the nucleus has a pull on electrons). Electrons shared in covalent bonds are pulled closer to the atom with a stronger nuclear pull. This creates a slight negative and a slight positive side in the bond. (Elements NOF have the strongest pull)

Question 39

Non-polar vs Polar

Answer 39

Non-polar = even distipution of charge, symmetrical. (eg: Methane / CH4) Polar = uneven distribution of charge, unsymmetrical (Hydrogen Fluoride / HF)

Question 40

Giant covalent structures + properties

Answer 40

Contain many (undefined number) of atoms, each joined to adjacent atoms by covalent bonds. These atoms are usually arranged into a giant regular lattice, extremely strong structures. Properties= very high melting points and usually can't conduct electricity (graphite is the exception)

Question 41

Silicon dioxide / Silica

Answer 41

Main component found in sand. All atoms (silicon and oxygen) are covalently bonded in a regular arrangement forming a giant covalent structure.

Question 42

Allotropes of carbon

Answer 42

Diamond and Graphite

Question 43

Diamond

Answer 43

Is a giant covalent structure and allotrope of carbon. Is extremely hard and has a high melting point as all carbon atoms are covalently bonded to 4 other carbon atoms - leaving no free electrons and no ions. Is insoluble in water and cannot conduct electricity.

Question 44

Graphite

Answer 44

Is a giant covalent structure and allotrope of carbon. Is insoluble in water, has a high melting point and is a good conductor of electricity. Each carbon atom is only covalently bonded to 3 other carbon atoms, leaving each atom with a spare elctron, forming a sea of delocalised electrons which can carry charge. Graphite is made of many layers joined by intermolecular forces, making it easy to break these layers and move around eachother, making graphite slippery.