Chapter 2 - Bonding Structure And Properties Of Matter Flashcards
How are ions made?
When electrons are transferred
Why do atoms gain or lose electrons?
To get a full outer shell
Atoms with a full outer shell are very stable
What happens when metals form ions and non metals?
Metals- lose electrons, positive ions
Non-metals- gain electrons, negative ions
What groups are most likely to form ions?
1&2
6&7
What type of ions will metals form?
Cations
What type of ions will non metals form?
Anions
What charge will ions from groups 1,2&6,7 form?
1- 1+
2- 2+
6- 6-
7- 7-
What are the three type of bonding?
Ionic
Covalent
Metallic
Describe what happens during ionic bonding
When a metal and a non-metal react together the metal atom loses electrons to form a positively charged ion and a non-metal gains these electrons to form negatively charged ions. These opposite be charged ions are strongly attached to one another by electrostatic forces. This is called an ionic bond
How can we show how ionic compounds are formed?
Dot and cross diagrams
However, they don’t show the structure of the compound, the size of the ions or how they’re arranged
What type of structure do Ionic compounds have?
Giant ionic lattice- the ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions in all directions of the lattice.
What are the properties of ionic compounds?
High melting points due to strong bonds between the ions
High boiling points due to strong bonds between the ions
When a solid, the ions are held in place so the compounds cant conduct electricity. When ionic compounds melt, the ions are free to move and they’ll carry electric current
They dissolve easily in water. The ions separate and are free to move in the solution, so they’ll carry electric current.
How do you work out the empirical formula?
1) Look at the diagram to work out what ions are in the compound
2) Work out the charges the ions will form
3) Balance the charges to the charge of the empirical formula is zero
What are covalent bonds?
When non metal atoms bond together they share pairs of electrons to male covalent bonds.
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong.
How many electrons are shared in covalent bonding
Each single covalent bond Provides one extra shared electrons for each atom
Each atom involved generally makes enough covalent bonds to fill up its outer shell. Having a full outer shell makes them very stable
What can use to draw covalent bonds
You can use the dot and cross diagram to show the bonding covalent compounds Electrons drawn in the overlap between the outer orbitals of two atoms are shared between those atoms
The displayed formula shows the covalent bonds as single lines between atoms
The 3-D model shows the atoms, the covalent bonds and the arrangement in space next to each other
What are simple molecular substances
Simple molecular substances are made up of molecules containing a few atoms joined together by covalent bonds
What are some examples of simple molecular substances
Hydrogen Chlorine Nitrogen Oxygen Methane Water Hydrogen chloride
What are the properties of simple molecular substances
The atoms within the molecules are held together by very strong covalent bonds. In contrast, the forces of attraction between the molecules are very weak
To melt or Boil a simple molecular compound you only need to break this feeble intermolecular forces and not the covalent bonds. This means that melting and boiling points are very low because the molecules are easily parted from each other
Most molecular substances or gases or liquids at room temperature
As molecules get bigger, the strength of the intermolecular forces increases some more energy is needed to break them and the melting or boiling points increase
Simple molecular substances don’t conduct electricity simply because they aren’t charged so there are no free electrons or ions
What are polymers
Polymers a long chains of repeating units. Lots of small units are linked together to form a long molecule that has repeating sections. All the atoms in a polymer are joined by strong covalent bonds
How do you find the molecular formula of a polymer
Write down the molecular formula of repeating unit in brackets and put an ‘n’ outside
What are the properties of a polymer
The 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
The intermolecular forces are still weaker than ionic or covalent bonds so they generally have lower boiling points then Ionic or giant molecular compounds
In giant covalent structures what are all the atoms bonded to each other by
All the atoms are bonded to each other by strong covalent bonds
What are the properties of Giant covalent structures?
They have very high melting and boiling points as lots of energy is needed to break the covalent bonds between the atoms
They don’t contain charge particles they don’t conduct electricity
