Bonding And Structure Chemistry Flashcards
What are the 3 states of matter
Solid liquid and gas
Describe a Solid
strong force of attraction, cant flow or move only vibrate, fixed lattice arrangement, cant be compressed and expand slightly when heated
Describe a Liquids
weak force of attraction, irregular structure, can flow and take shape of containers, can be compressed, expand when heated
Describe a gas
very weak force, free and far apart, constantly moving in random directions, can be compressed, speed up when heated
What is ionic bonding?
When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms, forming ions. The resulting compound is called an ionic compound. Reactions between metals and non-metals include: sodium + chlorine → sodium chloride.
Ionic compounds form what?
Giant structures where every positive ion is surrounded by a negative ion - this is called a giant ionic lattice
What are the characteristics of a giant ionic lattice
Three dimensional
Strong forces of attraction between the positive and negative ions these are called electrostatic forces
What are the key properties of ionic compounds?
Very high melting and boiling points because strong electrostatic forces require a great deal of heat energy to break.
Cannot conduct electricity when they are solids because the ions cannot move. They are locked in place by the strong electrostatic forces of attraction
Can conduct electricity when they are melted or dissolved in water because the ions can now move and carry the charge
What is covalent bonding?
A covalent bond forms when two non-metal atoms share a pair of electrons . The electrons involved are in the outer shells of the atoms. An atom that shares one or more of its electrons will complete its outer shell. Covalent bonds are strong – a lot of energy is needed to break them.
What is diamond made from?
Carbon atoms
Each carbon atom in a diamond has how many strong covalent bonds?
Four
Diamond cannot what? Why?
Conduct electricity as there are no free electrons to carry electrical charge
silicon dioxide has a what? Why?
Very high melting and boiling point due to a huge number of strong covalent bonds that must be broken which takes a great deal of energy
Graphite is an excellent conductor of what two things?
Electricity and heat
In the case of graphite each carbon atom forms how many covalent bonds?
Three
The hexagonal rings of carbon atoms are arranged in what?
Layers- there are no covalent bonds between the layers so they can slide this makes graphite slippery
What are delocalised electrons?
Electrons that are not attached to any individual atom so are free to move
Why do we use to make a mixture harder?
An alloy
What is an alloy?
A mixture of metals
What is metallic bonding
Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons and positively charged metal ions. It may be described as the sharing of free electrons among a structure of positively charged ions.
Metallic bonding is the electrostatic attraction between positive metal ions and delocalised electrons. The organisation of the metal ions and the free-moving electrons give metals certain properties, such as malleability and ability to conduct heat and electricity.
Properties of covalent bonding
The boiling/melting points of covalent compounds are low.
They are soft in nature and relatively flexible.
These compounds do not possess electrical conductivity.
They have lower values of enthalpy of fusion/vaporization
Properties of ionic bonding
high melting and boiling points, poor conductivity in solid state, and high conductivity in aqueous solutions. →How does Ionic Bonding
Properties of metallic bonding
strong, so metals can maintain a regular structure and usually have high melting and boiling point
How can you use the periodic table to help you remember charges on ions?
Look at the group number:
Group 1 form +1 ions
Group 2 = +2
Group 3 = +3
Group 4 = don’t form ions
Group 5 = -3
Group 6 = -2
Group 7 = -1
Group 0 don’t form ions
What are the two types of covalent structures?
Giant covalent and simple molecular structures
What are the properties of simple molecular substances?
Gases, liquids (with low boiling points) or solids (with low melting points), usually non conductors.
Why do simple covalent compounds have low melting and boiling points?
They have weak forces of attraction between their molecules that take little energy to overcome.
What are the properties of giant covalent structures?
Solids with very high melting and boiling points.
What are some examples of giant covalent structures?
Diamond, graphite (both forms of carbon), silicon dioxide (sand)
Describe the structure of diamond and graphite.
Diamond-each carbon atom forms 4 covalent bonds to other carbon atoms forming a rigid, giant 3D structure.
Graphite-each carbon only forms 3 covalent bonds to other carbons, creating layers of hexagons between which there are delocalised electrons (one e- per carbon).
Why do metals conduct electricity?
They have delocalised electrons which can flow when an electric field is applied across it.
