Structure and bonding Flashcards
Isotopes
Different atomic forms of the same element, which have the same number of protons, but different number of neutrons
Describe the physical and the chemical properties of isotopes of the same element
Same chemical properties
Different physical properties
Calculate the RAM of Cl. If there is 75% of Cl35 and 25% of Cl37
(3575+3725)/100=35.5
RAM
Relative atomic mass. Relative to 1/12 of Carbon 12
List 3 types of bonding
1) Ionic 2) Covalent 3) Metallic
Ionic bonding
Is the transfer of electrons between metals and non-metals
What happens to metal atoms when they form an ionic bond?
They lose electrons to form positive ions (cations)
What happens to non-metal atoms when they form an ionic bond?
They gain electrons to form negative ions (anions)
Describe the forces of attraction in an ionic compound
Strong electrostatic attraction between the positive and negative ions
Give an example of a giant crystal structure (2)
1) Sodium chloride 2) Magnesium oxide
Describe the arrangement of of ions in a giant structure
The alternate positive and negative ions in an ionic solid are arranged in an orderly way in a giant ionic lattice structure
Describe properties of ionic compounds (6)
1) Strong bonding forces make the structure hard. They are not malleable, but brittle
2) Have a high melting and boiling points
3) The greater the charges of the ions the stronger the forces of attraction
4) Many soluble in water. NOT ALL
5) Solid crystals do not conduct electricity
6) Ionic compound melted or dissolved in water will conduct electricity
Why solid ionic crystals don’t conduct electricity?
Particles are held in place, therefore no movement of charge
Give an example of 2 ionic compounds with different melting points and different charges of ions
1) Mg +2 O -2 (2852C) 2) Na+Cl- (801C)
Covalent bonding
Share of electrons between non-metals ONLY
What is Cl2
A molecule with no overall charge
Describe the attraction forces between molecules
Weak forces of attraction
Describe the attraction forces of a covalent bonding
Very strong
Describe and explain Melting point of a covalent compound
Low, forces of attraction between individual molecules are weak
Describe and explain Physical state at rtp of a covalent molecule
Gasses or liquids with low boiling points or solids with low melting point, weak forces of attraction between the molecules
Describe and explain Electrical conductivity of a covalent molecule
Do not conduct electricity, the molecules have no overall charge
Describe and explain solubility in water of a covalent molecule
Most are insoluble in water, strong forces of attraction within the molecule
Describe physical and chemical properties of diamond (6)
1) Each carbon atom has 4 covalent bonds with its neighbours
2) The atoms are arranged in a giant covalent structure
3) Very high melting point 3500
4) Very hard
5) Not soluble in water
6) Doesn’t conduct electricity
Describe physical and chemical properties of graphite(6)
1) Has a layered structure
2) Each carbon atoms forms 3 covalent bonds, which leaves the fourth electron in the bonding level delocalised over the whole of the sheet
3) Delocalised electrons are free to move, therefore conduct electricity
4) Soft
5) Very high melting point 3500
6) Insoluble in water
Covalent substances can either be…(2)
1) Giant covalent structure 2) Simple molecular structure
Giant covalent structures
Huge 3D networks of atoms with high melting and boiling points
Properties of metals(7)
1) Conduct electricity
2) Conduct heat
3) Most metals are hard
4) High melting and boiling points
5) Typically have silvery surface
6) Very malleable
7) Have a high density
Metallic bonding
Array of positive ions in a sea of electrons
Describe forces of attraction in a metallic bonding
Strong electrical forces of attraction between free and mobile electrons and the ‘immobile’ positive metal ions
Factors affecting the rate of reaction (5)
1) Concentration
2) Catalyst
3) Surface area
4) Temperature
5) Pressure (for gasses)
Rate of reaction
Number of successful collisions per second
Why concentration results in increase of reactions?
More particles available for collision
Why surface area results in increase of reactions?
More particles are exposed to the surface so there are more successful collisions
How do catalysts work?
They provide an alternative pathway for reactions, so they occur at lower activation energy. DO NOT REACT THEMSELVES
