Bonding, Structure and Properties of Matter Flashcards
Ion
Charged particle formed when an atom/molecule loses/gains electrons to get a full outer shell
What happens when metals form ions
- lose electrons
- form positive ions
What happens when non-metals form ions
- gain electrons
- form negative ions
How is charge of an ion determined
number of an electrons lost
Most likely groups to form ions
- group 1
- group 2
- group 6
- group 7
Types of bonds
- ionic
- covalent
- metallic
ionic bond
Strong attraction between oppositely charged ions by electrostatic forces, caused by metals and non-metals reacting together
What happens in an ionic bond
- metal atom loses electrons
- electrons transferred to non-metal
What diagram shows ionic bonds
Dot and cross
Limitations of dot and cross diagram
Doesn’t show 3 dimensional nature of structure
Structure of ionic compound
Giant ionic lattice
Structure of giant ionic lattice
- ions form closely packed regular lattice arrangement
- strong electrostatic forces of attraction between oppositely charged particles in all directions in lattice
Properties of ionic compounds
- high melting points
- high boiling points
Why do ionic compounds have high melting/boiling points
There are strong electrostatic forces of attraction between ions that take a lot of energy to overcome
When can ionic compounds conduct electricity
When molten
Molten
Metled
Why can ionic compounds conduct electricity when molten
Ions are free to move and carry a charge
When can’t ionic compounds conduct electricity
When solid
Why can’t ionic compounds conduct electricity when solid
ions held in place so can’t carry a charge
What happens to some ionic compounds in water
- they dissolve
- ions separate and are free to move in solution
- carry electric charge and conduct electricity
Empirical formula
- what atoms are in an ionic compound
- includes number of each atom
Covalent bond
- bond between non-metals
- electrons shared to get full outer shells
- positive nuclei attracted to shared electrons through electrostatic forces
Diagram to show covalent bonds
Dot and cross
Simple molecular substances
Substances made up of molecules containing a few atoms joined together by covalent bonds
Properties of simple molecular substances
- atoms within molecules held together by very strong covalent bonds
- forces of attraction between molecules very weak
- low melting/boiling points
- usually gas/liquid at room temperature
- melting/boiling points increase as molecules get bigger
- don’t conduct electricity
Why do simple molecular structures have low melting/boiling points
To melt/boil, only have to break weak intermolecular forces (easy to do)
Why do melting/boiling points of simple molecular substances increase as they get bigger
- strength of intermolecular forces increases
- more energy needed to break them
Why can’t simple molecular structures conduct electricity
Not charged so there are no free electrons to carry a charge
Polymers
Long chains of repeating small units, forming a long molecule that has repeating sections
How are atoms in polymers linked
Strong covalent bonds