Bonding-Types of Solids Flashcards
What are Ionic Substances Composed of?
Positive Cations, and Negative anions
What are the forces holding ions together in ionic solids?
Electrostatic forces of attraction.
Are ionic substances electrically neutral?
Yes as they have an equal number of positive and negative charges.
Properties of ionic solids?
- High Melting Point
- Soluble in Polar solvents
- Conductive when ions are free to move (molten or aqueous)
- Very hard
- Brittle easily brake when force applied
What are molecular substances
composed of?
Discrete molecules
Forces holding molecules together in a molecular substance?
Weak Van der Waal forces of attraction.
Properties of Molecular Substances?
- Low Melting Point
- Polar molecules dissolve in polar solvents, vice versa
- Do not conduct, no free to move charged particles
- Soft
- Solids Shatter
What are intramolecular bonds?
Strong covalent bonds between atoms in a molecule
What are intermolecular bonds?
Weak forces of attraction between molecules
What do Lewis diagrams of molecules show?
Where covalent bonds are located and where lone pair electrons are located.
What shape is a molecule with 4 regions of electron density, of which two are bonded?
Bond angles?
Bent
Electronegativity is the measure of an atoms ability to?
Attract electrons to itself
What atom on the periodic table is most electronegative?
Fluorine.
If a molecule is polar it has a molecular….?
Molecular dipole. (Bond dipoles do
not cancel)
Metals are found on what side of the periodic table?
Left hand side.
What do metallic substances consist of?
Positively charged metal nuclei, surrounded by a ‘sea’ of delocalised electrons.
Metals are held together by what?
Very strong, non-directional electrostatic forces of attraction between metal nuclei and nearby electrons.
Are delocalised electrons free to move through the substance even when solid?
Yes
Properties of Metals?
-High Melting Point.
-Not soluble
-Can conduct due to delocalised electrons
Malleable, and ductile- because of the nondirectional bonding between metal nuclei and delocalised electrons.
What does ECN stand for?
Extended covalent networks- solids
What do Covalent Networks consist of?
A large number of non-metal atoms covalently bonded together.
What are the covalent network solids at NCEA level 2?
Diamond- Carbon
Silicon Dioxide- SiO2
Graphite- Carbon
Properties of Covalent Network solids?
- Very High Melting Point
- Insoluble
- Conductive if delocalised electrons are present (graphite)
- diamond, and silicon dioxide very hard, graphic soft.
What is different about graphite, compared to other ECN?
It consists of sheets of Carbon atoms, with strong intramolecular bonds between atoms, but weak intermolecular bonds between the sheets. Making it soft and slippery. It also has one delocalised electron on each atom, that is free to carry electrical current.
