C3: Structure and Bonding Flashcards
What are the 3 states of matter?
Solids
Liquids
Gases
What is all matter made up of?
Particles
What is particle theory and how are particles represented?
Particle theory describes the movement and arrangement of particles in different states of matter (solids, liquids, gases)
Particles are represented as small solid spheres
Describe the particle theory representation in solids?
Arrangement: Particles in a solid are packed closely together in a fixed arrangement
Movement: They vibrate constanty
Describe the particle theory representation of liquids?
Arrangement: Particles in a liquid are close together in a changing, random arrangement
Movement: They can move around
Describe the particle theory representation of gases?
Arrangement: Particles in a gas are much further apart in a random arrangement
Movement: They move around very quickly
What happens to the particles when a solid becomes a liquid?
As the temperature increases, the particles in a solid vibrate faster
At the melting point enough energy is transferred to break the forces between the particles
The particles then break away from their fixed position and start to move around and a liquid is formed
When does a solid become a liquid?
At its melting point
What happens to the particles when a liquid becomes a gas?
As the temperature increases, the particles in a liquid vibrate faster
As more energy is transferred to the substance some of its particles can escape the liquid before boiling point is reached - this means the liquid is evaporating
At the boiling point, bubbles of gas form within the liquid and rise up to the surface and a gas is formed
What can you say about the forces between particles in substances with higher / lower boiling and melting points
Substances with higher boiling and melting points = stronger forces between their particles
Substances with lower boiling and melting points = weaker forces between their particles
What are the limitations of the particle model of solids, liquids and gases?
The particle model assumes that particles are solid with no forces between them
However the limitations are:
-> Particles can be atoms, molecules or ions
-> Can contain many atoms
-> Vary in size
-> Aren’t solid or spherical
When are compounds formed?
Compounds are formed when 2 or more elements react together
How do atoms of elements join together?
By sharing electrons or by transferring electrons to achieve stable electronic structures
Which atoms already have stable electronic structures?
Noble gases - group 0 elements
What is covalent bonding?
When non-metallic elements join together by sharing electrons
What is produced when metallic elements react with non-metallic compounds?
When metals react with non-metals they form ionic bonds
What happens in ionic bonding?
The metallic atoms lose electrons and form positive ions (cation)
The non-metallic atoms gain electrons and form negative ions (anions)
The ions have a full outer shell of electrons - the same as noble gases
The two oppositely charged ions attract each other in the compound - this is ionic bonding
What happens to group 1 elements in ionic bonding?
Group 1 elements are metals - they have 1 electron in their highest energy level (outer shell) which they lose to the non-metal
They form +1 charged ions
These react with Group 7 elements (non-metals) that form -1 charged ions
What happens to group 2 elements in ionic bonding?
Group 2 elements are metals - they have 2 electron in their highest energy level (outer shell) which they lose to the non-metal
They form +2 charged ions
These react with Group 6 elements (non-metals) that form -2 charged ions
What can be used to show the electrons in the outer shell of an atom and draw this reaction for Na + Cl -> NaCl
Dot and cross diagrams
Draw NaCl reaction as a dot and cross and check the answer
When are ionic compounds formed?
When metals react with non-metals
What holds ionic bonds together?
Ionic bonds are held together by strong forces of attraction between oppositely charged ions
These ionic bonds can come together to form a giant structure also known as a giant lattice
What is a giant lattice / structure?
A huge 3D network of atoms / ions as seen in ionic bonding
Why are ionic compounds usually solid at room temperature?
There are strong electrostatic forces of attraction between the oppositely charged ions
These require lots of energy to overcome and break these bonds hence they have HIGH boiling and melting points