Chapter 3- Structure And Bonding Flashcards
What are the three states of matter?
Solid, Liquid, Gas
The particles in a solid are…
They are packed closely together and vibrate around fixed positions
The particles in a liquid are…
The particles in a liquid are packed closely together but can slip and slide over each other in random motion
The particles in a gas are…
The particles in a gas on average have a lot of space between them and zoom around freely
What charge will a group 6 and group 2 element form?
Group two will form two plus
Group six will form two minus
How do elements form compounds?
By gaining or losing electrons or sharing electrons
What combinations of groups can form ionic compounds
7
1
6
2
What are ionic compounds held together by?
They are held together by strong forces of attraction between their oppositely charged ions. This is called ionic bonding.
What happens when metals form ions?
They lose electrons from their outer shell to form positive ions
What happens when non metals form ions?
They gain electrons in their outer shell to form negative ions
What charge would the ions in group 1,2,6 and 7 have?
1, +1
2, +2
6, 2-
7, 1-
Name 3 properties of ionic compounds
They have high melting and boiling points due to the many strong electrostatic attractions.
When ionic compounds are solid they are held in place and don’t conduct electricity when they are melted they are able to conduct electricity because the atoms are free moving.
Ionic compounds dissolve easily in water. When dissolved they conduct electricity
What is the empirical formula?
You will be given a structure and asked to look at the charges and work out the formula for the two atoms
What kind of atoms covalent bond?
Non metals
Describe the simple molecular bond of hydrogen
Hydrogen atoms have just one shell they only need one more to complete the first shell. The covenant bond consists of two hydrogen atoms
Describe the simple molecular bond of chlorine
Each chlorine atom only needs one more electron to complete the outer shell. So two chlorine atoms form a single covenant bond
Describe the simple molecular bond of oxygen
Only needs two more electrons.
Two oxygen atoms share two pairs of electrons making a double covalent bond
Describe the simple molecular bond of nitrogen
Nitrogen atoms need three more electrons.
So two nitrogen atoms share three pairs of electrons, it creates a triple bond
Describe the simple molecular bond of methane
It forms 4 covenant bonds with hydrogen
Describe the simple molecular bond of water
In water molecules the oxygen forms two covenant bonds with hydrogen forming two single covalent bonds
Is the melting point high or low of simple molecular substances
It’s low because the forces between the molecules is weak not the force between the atoms
Do molecular compounds conduct electricity, why?
They don’t because they aren’t charged
What state are most molecular substances at room temperature?
Most are either liquid or gas
Why is a polymer?
It’s lots of small units that are linked together to form a long molecule that has repeating sections. All of the atoms in a polymer are joined by covenant bonds .
What state are polymers at room temperature?
They have strong molecular bonds so most are solid.
Describe the melting and boiling points of polymers
The bonds are still weaker than ionic and giant molecular compounds so they have a lower boiling point then them
Give 3 properties of giant covenant structures
All the atoms are bonded to each other by strong covenant bonds.
They have high melting and boiling points.
They don’t contain charged particles so they don’t conduct electricity
Describe the structure of a diamond giant structure
Each carbon atom forms 4 covenant bonds in a very rigid giant covalent structure. It has a very high melting point. It doesn’t conduct electricity because it has no free electrons or ions
Describe the structure of a graphite giant structure
Each carbon atom forms thee covenant bonds to create layers of hexagons. Each carbon atom also has one delocalised electron. There is no strong bonds between the layers of hexagons so they slide over each other. It has got a high melting point. It is an exception and conducts thermal and electrical energy
Describe what silicon dioxide is
It is sand and Is made up of silicon and oxygen
What is graphene?
Graphene is a sheet of carbon dioxide joined together in hexagons the sheet is just one atom thick. The multiple connections make it very strong. It’s also incredibly light so can be added to materials to improve their strength. It can conduct electricity
Why can graphite conduct electricity?
Because only three out of carbons 4 outer electrons are used in bonds so each carbon atom has one electron that is delocalised .
What are fullerenes?
Fullerenes are molecules of carbon shaped like closed tubes or hollow balls.
Describe a fullerene
They’re mainly made up of carbon atoms arranged in hexagons but can contain pentagons and heptagons.
Fullerenes can be used to cage and hold other molecules
Fullerenes have a huge surface area
Give three uses of fullerenes
They can be used to deliver drugs into the body via encasing the drug.
They can form nanotubes
They make great lubricants
What are nanotubes?
Fullerenes from nanotubes, tiny carbon cylinders.
The ratio between the length and the diameter is high.
They can conduct both electrical and thermal energy.
They have a high tensile strength.
They are used because they are strong but very light
What is the buckminsterfullerene?
It is the first fullerene to be discovered the formula is C60 and forms a hollow there
What are delocalised electrons?
The electrons in the outer shell of the metal atom are delocalised there are strong connections between the positive metal ions and the shared negative electrons
Describe the melting point of metals metallically bonded
The forces between the metal atoms and the delocalised sea of electrons are very strong and are hard to break. It means most compounds with metallic bonds have very high melting points and are generally solid at room temperature.
Are metals good conductors of energy? Why?
Yes they conduct electricity well because of the delocalised electrons carrying the current throughout the whole structure
Are metals malleable?why?
They are because the layers of atoms slide over each other, it means they can be shaped relatively easily
Are alloys malleable?why?
They aren’t because the introduction of a different metal obstructs the regular and uniform formation of atoms in a metal and means that the atoms cannot slide over each other very well
What are alloys?
They are metals that have been combined with other metals or elements to create stronger metals, they are harder and are therefore more useful than regular metals
4 key words to remember when describing a change of state
Melting
Boiling
Freezing
Condensing
