topic 2 bonding Flashcards
Glass is made by heating sand and two other materials why?
limestone and sodium carbonate
Stronger so less easily damaged
Why does manganese oxide conduct electricity as a liquid?
Ions move around in the liquid
Why is graphite good electrical conductor, soft, and slippery?
Bonds are covalent
Only 3 electrons per carbon atom used
1 Electron per carbon atom is the delocalised
they can move through the structure carrying electrical charge
So graphite conducts electricity
Compare the structure and bonding of carbon dioxide, magnesium oxide, silicone dioxide
carbon dioxide and silicon are made up of atoms, but magnesium is made up of ions
Silicone and magnesium are giant structures and carbon dioxide is a small/weak intermolecular forces
what is ionic bonding?
Ionic bonding is the electrostatic attraction between positive and negative irons. It is a relatively strong attraction.
how are ionic compounds held together?
They are held together in a giant lattice
It’s a regular structure that extends in all directions in a substance
Electrostatic attraction between positive and negative ions hold the structure together
State the PROPERTIES of ionic substances
High melting and boiling points(strong electrostatic forces between oppositely charge ions)
do not conduct electricity when solid
conduct when Moulton are dissolved in Water– ions are free to move
how are ionic compounds formed? Explain in terms of MhO case.
reaction of metal with a non-metal
Electrons transfer occur– metal gives away its outer shell electrons to a non-metal
Mg is in group 2, so has two available out of shell electrons
O is in group 6, so can accept two electrons to get a full shell configuration
Mg becomes MG2+
O becomes O2-
What is covalent bond?
Covalent bond is a shared pair of electrons between two atoms
describe the structure and properties are simple molecular convalent substances
Do not conduct electricity
Small molecules
Weak intermolecular forces therefore low melting and boiling points
how does intermolecular forces change as the mass less size of the molecule increases?
They increase. That causes melting/boiling points to increase as well.
What are polymers? What are thermos softening polymers?
Polymers are very large molecules with atom linked by convaent bonds
thermosoftening polymers – special type of polymers: they melt/ soften when heated. There are no bonds between the polymer chains. Strong intermolecular forces in the structure is solid at room temperature. These forces are overcome with heating – polymer melts.

what are giant convalent substances?
solids, atoms, convalently bonded together in a giant lattice
High melting/boiling pints – strong, convalent bond
Mostly don’t conduct electricity
Diamond, graphite, Silicon dioxide 
what is metallic bonding?
Forces of attraction between delocalised electrons and nuclei of metal ions
describe the properties of metals
High melting/boiling points
Good conductors of heat and electricity
Malleable,soft
what are all alloys? Why are they harder than pure metals?
allies: mixture of metals with other elements, usually metals
Different sizes of atoms distort the layers, so they can’t slide over each other, therefore alloys are harder than pure metals
What are the limitations of a simple model?
there are no forces between spheres and atoms, molecules and ions are solid spheres - this is not true
What does the amount of energy needed to change date from solid to liquid or liquid to gas depend on?
The strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the force is between the particles the higher the melting and boiling point of the substance.
a pure substance will melt or boil at?
fixed temperature
and mixture will melt over range of temperatures
State the use of nano particles
Medicine, electronics, deodorants, sun creams
what are fine and caused particles?
Fine particles 100-2500 nm diameter
coarse particles(dust) 2500-10 5
Why do Nana particles have properties different from those for the same materials in bulk?
High surface area to volume ratio
