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GCSE chemistry > Covalent Bonding > Flashcards

Covalent Bonding Flashcards

1
Q
A
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2
Q

How are ions formed?

A
  • In an atom the number of electrons is equal to the number of protons so the atoms are neutral (they have no overall charge)
  • when atoms lose or gain electrons they become ions
  • metal atoms usually lose electrons to form positive ions (cations), this is called oxidation
  • non-metal atoms usually gain electrons to form negative ions (anions), this is called reduction.
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3
Q

What does an atom which loses 2 electrons have a charge of?

A

2+

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4
Q

What does an atom which gains 2 electrons have a charge of?

A

2-

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5
Q

What are giant ionic structures?

A
  • Ionic, giant covalent and metallic bonding products have giant structures made up of oppositely charged ions
  • the ions are arranged in a regular three-dimensional giant lattice structure with alternating positive and negative ions
  • the ions are held together by very strong electrostatic forces of attraction in all directions
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6
Q

What type of bonding involves a metal and non metal?

A

Giant ionic bonding

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7
Q

What are the properties of ionic compounds?

A

HIGH MELTING AND BOILING POINTS
-a lot of energy is needed to overcome the strong electrostatic attractions between the oppositely charged irons in the giant lattice.
-The higher the charges on the ions the stronger the electrostatic attractions so the higher the melting and boiling points
-for example MGO has a higher melting point than NaCl
DONT CONDUCT ELECTRICITY IN SOLID STATE
-This is because the ions are in fixed positions and cannot move
-however they will conduct electricity when melted (molten) or in solution (dissolved in the water) because the ions are free to move and carry the charge
BRITTLE
-The crystals can be split if force is applied as ions of the same charge come into contact and repel each other
- ionic compounds are often soluble in water as the polar water molecules are able to attract the irons and pull them out of the lattice

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8
Q

What is the order of the charges of the different elements in each of the different groups (1-7)

A

1+,2+,3+(group 3), 2+,3-,2-,1-

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9
Q

What type of bonding involves only non metals?

A

Covalent bonding

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10
Q

What type of bonding involves only metals?

A

Giant metallic bonding

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11
Q

What are the two types of structures of covalent bonding?

A

Giant (e.g diamond)and simple molecular

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12
Q

What particles does giant covalent bonding use?

A

Carbon atoms

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13
Q

What particles does simple molecular covalent bonding use?

A

Molecules

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14
Q

What forces does giant covalent bonding use?

A

Covalent bonds

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15
Q

What forces does simple molecular bonding use?

A

Intermolecular forces

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16
Q

Is the melting point of giant covalent bonding high or low?

A

High because of the strong covalent bonds

17
Q

Is the melting point of simple molecular covalent bonding high or low?

A

Low because there are only weak intermolecular forces

18
Q

What are the properties of covalent bonding?

A

GIANT COVALENT
-doesn’t conduct electricity because all the electrons in the outer shells of the carbon atoms are tightly held in the covalent bonds between atoms
-hard, insoluble in all solvents, conducts heat well
SIMPLE MOLECULAR COVALENT
-tend to be gases/liquids/solids with low melting or boiling points because not much energy is needed to break the weak intermolecular forces of attraction (NO covalent bonds are broken)
-melting and boiling points increase as mass increases (e.g halogens) because the intermolecular forces become stronger as mass increases
-doesn’t conduct as there are no charges and all electrons are held tightly in the covalent bonds
-insoluble in water but soluble in organic solvents

19
Q

What is the structure of ionic bonding?

A

Giant lattice (alternating + and - electrons)

20
Q

What type of structure does metallic bonding have?

A

Giant- a giant lattice (regular arrangement) of positive ions and delocalised electrons

21
Q

What particles are used in metallic bonding?

A

Positive ions in a sea of negatively charged delocalised electrons

22
Q

What forces does metallic bonding make?

A

Strong Electrostatic attractions between the positive ions and delocalised electrons. There are no individual molecules

23
Q

What are the properties of metallic bonding?

A
  • high melting and boiling points because of the strong electrostatic attractions between positive atoms and negative delocalised electrons
  • the higher the charge on the metal ions, the stronger the electrostatic attractions and so the higher the melting point
  • good at conducting due to delocalised electrons which can move throughout the structure
  • malleable and ductile because the LAYERS of positive ions can easily slide over each other without breaking the attractions to the delocalised electrons
24
Q

What is a giant ionic lattice?

A
  • The millions of alternative positive and negative ions in ionic compounds which are arranged in a regular way
  • it is held together by strong electrostatic attractions between the p and n ions
  • giant means there are no individual molecules. The electrostatic attractions extend throughout the structure in all directions
  • never use the word molecule when referring to an ionic compound
25
Q

Does magnesium oxide have stronger or weaker electrostatic attractions than sodium chloride?

A
  • Stronger, because in magnesium oxide 2+ ions are attracting 2- ions
  • in sodium chloride the electrostatic attractions are weaker because they are only by 1+ and 1- irons
  • although both have the same structure magnesium oxide is stronger
26
Q

What is covalent bonding?

A
  • between non metal atoms
  • a pair of electrons is shared between two atoms
  • the atoms are held together by the strong electrostatic attraction between the nuclei (positively charged) of the bonding atoms and the shared pair of electrons (negatively charged)
27
Q

What does diatomic mean?

A
  • Contains 2 atoms
  • atoms share electrons so they have the same number of electrons in their outer shell as a noble gas
28
Q

What is the difference between intermolecular and electrostatic attractions?

A
  • intermolecular attractions are between molecules and are not very strong
  • Electrostatic attractions occur between positive charges and negative charges. The positively charged protons in the nucleus attract the negatively charged electrons in the electrons shells, there is an electrostatic attraction between them.
29
Q

What are the forms (allotropes) of carbon?

A

Diamond, graphite, fullerene

30
Q

Describe the structure and properties of diamond

A
  • each carbon atom forms four strong covalent bonds to four other carbon atoms
  • this forms a 3D giant covalent structure, it is not a molecule
  • diamond has high melting and boiling points and is very hard as a lot of energy is needed to break the strong covalent bonds that extrend throughout the giant structure
  • it doesn’t conduct electricity as the electrons are tightly held in the covalent bonds so cannot move
31
Q

Describe the structure and properties of graphite

A
  • this is still giant covalent but it has a layer structure
  • graphite is soft bas the forces between layers are weaker so they can slide over each other easily
  • graphite still has high melting and boiling points as a lot of energy is needed to break the strong covalent bonds
  • graphite does conduct electricity as each carbon atom forms three covalent bonds to three other carbon atoms. The fourth electron from each carbon can move throughout the layers as delocalised electrons
32
Q

Describe the structure and properties of fullerene

A
  • fullerene has the formula C60
  • it is a molecule and so it has a simple molecular structure, not a giant structure
  • it has a lower melting and boiling point than diamond and graphite and it is softer than diamond because not a lot of energy is needed to break the weak intermolecular forces
  • it doesn’t conduct electricity because the electrons are not free to move from one molecule to another
33
Q

What is an alloy?

A
  • a mixture of a metal with other metals or carbon(e.g steel is a mixture of iron and carbon)
  • alloys are harder that pure metals because the different sized atoms break up the regular lattice arrangement and make it more difficult for the LAYERS of ions to slide over each other
34
Q

What is a lattice?

A

A regular arrangement of positively and negatively charged particles in rows

35
Q

Draw the structures of diamond, graphite and fullerene

A

(See answers in folder)

GCSE chemistry (9 decks)

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