Topic 2 Flashcards
When are ions made?
When electrons are transferred
What are ions?
Ions are charged particles - they can be single atoms or groups of atoms
Why do atoms lose or gain electrons?
They are trying to form a full outer shell.
What happens when non-metals and metals form ions?
The non-metals gain electrons into their outer shell to form negative ions. The metals lose electrons from their outer shell to form positive ions.
What is the number of electrons lost or gained the same as?
The charge of the ion
e.g
if 2 electrons are lost = 2+
If 3 electrons are gained = 3-
What groups are most likely to form ions?
Group 1(1+) and 2(2+) are metals and they lose electrons to form positive ions (cations).
Group 6(2-) and 7(1-) are non-metals. They gain electrons to form negative ions (anions).
what is ionic bonding?
When a metal and non-metal react together. The metal atom loses electrons to form a positive charged ion and the non-metal gains these electrons to form a negatively charged ion. these oppositely charged ions are strongly attracted to one another by electrostatic forces.
What structure do ionic compounds have?
regular lattice / giant ionic lattice
What are the similar properties that all ionic compounds have?
-High melting points and high boiling points due to the many strong bonds between the ions.
-conduct electricity when in liquid a form
-Strong ionic bonds (held together by electrostaic forces)
How are covalent bonds made?
When non-metal atoms bond together, they share pairs of electrons to make covalent bonds. The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces.
Where do covalent bonds happen?
In compounds of non-metals and in non-metal elements
What are simple molecular substances made up of?
molecules containing a few atoms joined together by covalent bonds. substances containing covalent bonds usually have simple molecular structures
What are polymers?
Long chains of repeating units. In polymers, lots of small units are linked together to form a long molecule that has repeating sections.
What are all the atoms in a polymer joined by?
Strong covalent bonds
Compare intermolecular forces between polymers and simple covalent molecules.
Intermolecular forces between polymer molecules are larger than between simple covalent molecules, so more energy is needed to break them. This means most polymers are solid at room temperature.
Compare intermolecular forces to ionic and covalent bonds.
Intermolecular forces are weaker than ionic or covalent bonds, so they generally have lower boiling and melting points than ionic or giant molecular compounds.
What are macromolecules?
Giant covalent structures.
What are allotropes?
different structural forms of the same element in the same physical state
What are the main examples of giant covalent structure?
Diamond, Graphite (both made from carbon atoms) and silicon dioxide (silica).
Explain the structure of a Diamond (a giant covalent bond).
Each carbon atom forms four covalent bonds in a very rigid giant covalent structure. This makes diamond really hard. These strong covalent bonds take a lot of energy to break and give diamond a very high melting point. It doesn’t conduct electricity because it has no free electrons.
Explain the structure of a Graphite (a giant covalent bond).
Each carbon atom forms three covalent bonds to create layers (that are 1 atom thick) of hexagons. Each carbon atom also has one delocalised (free) electron. Has a high melting point
Explain the structure of a Silicon dioxide (a giant covalent bond).
Sometimes called silica, this is what sand is made of. Each grain of sand is one giant structure of silicon and oxygen.
What are Fullerenes?
Fullerenes are molecules of carbon shaped like closed tubes or hollow balls.
What are Fullerenes made up of?
carbon atoms arranged in hexagons, but can also contain pentagons (rings of five carbon atoms) or heptagons (rings of seven carbon atoms).
