7 - bonding and structure Flashcards
Define ionic bond
The electrostatic attraction between 2 oppositely charged ions
What do ionic bonds form between?
A metal and a non-metal
How do you draw dot and cross diagrams for atoms?
Draw a circle for the nucleus and put the symbol of the element inside it
Don’t draw any rings
Draw the outer shell without a ring around the nucleus
Draw the electrons as crosses in one atom and as dots around the other element
Put electrons in spin pairs whenever possible
How do you draw ions as dot and cross diagrams and how do you draw their reaction?
Draw the metal nucleus with no electrons on the outside (all been taken)
Put square brackets around it and put the charge as a superscript to the brackets
Draw the non-metal nucleus with the outer electrons of the atom as crosses and the added electrons (from the metal) as dots
Put electrons in spin pairs
Put brackets around the non-metal ion etc. as well
If you need more than one of an ion, but a big number before the brackets
What is the charge of the ions in each of the groups?
Group 1 have +
Group 2 have 2+
Group 13 have 3+ except for boron (a non-metal)
Group 14 doesn’t form ions
Only the non-metals in group 15 form 3-
Only the non-metals in group 16 form 2-
Group 17 have -
Group 18 don’t form ions because they are noble gases
Define giant ionic lattice
A 3D structure of oppositely charged ions, held together by strong ionic bonds
What are the 2 main properties of ionic compounds?
Conduct electricity when molten or liquid
High melting and boiling points
Exist as giant ionic lattices
Why do ionic compounds conduct electricity as liquid or molten?
When you melt or boil, you pull apart ionic bonds
Allowing the ions (charged particles) to move and so they can carry a current
As a solid, the ions aren’t free to move so current isn’t carried
Why do ionic compounds have high melting and boiling points?
Very strong electrostatic attractions between oppositely charged ions so a large energy is needed to pull them apart
What effect does the charges of ions have on the ionic bonds?
A bond made by higher charges is harder to overcome
Requires more energy to overcome
What is a polar solvent?
A solvent which has slight negative and positive charges
What is the most common polar solvent?
water
How are ionic compounds and polar solvents linked?
Ionic compounds dissolve in polar solvents
Why do ionic compounds dissolve in polar solvents?
The ions of the compound are attracted to the small positive and negative charges of the polar solvent
What are metallic bonds?
Strong electrostatic attractions between positive metal ions and delocalised electrons
What is a giant metallic lattice?
The 3D structure of positive metal ions and delocalised electrons which are bonded by strong metallic bonds
Where do the delocalised electrons in metals come from?
Electrons leave the outer shells of metal atoms so that they are free to move about the structure
The loss of electrons from the metal atoms makes them positive metal ions
What are the 8 properties of metals?
Conduct electricity and heat
Malleable
Ductile
Strong
High melting and boiling points
Sonorous
Shiny
Not soluble in water
Why do metals conduct electricity and heat?
The free, delocalised electrons can carry the current through the structure
What do malleable and ductile mean?
Malleable means that it can be compressed without breaking
Ductile means it can be stretched / pulled out without breaking
Why do metals have high melting and boiling points?
The strong metallic bonds require a large amount of energy (and high temperature) to overcome
What does sonorous mean?
It makes a ringing noise when hit
define covalent bond
What is a covalent bond?
When does covalent bonding occur and why?
Reactions between 2 non-metals
So that all atoms have a full outer shell