Unit 2 Flashcards
Define: chemical bond
Force of attraction between 2 atoms or ions
What are the 2 types of chemical compands (describe)
Ionic and molecular
Ionic = transfer
Molecular = sharing
Properties of ionic compounds
Solid, definate geometries, hard, brittle, high melting point and boiling point , conduct electrety (electrolyte)electricty conductivty in water
Explam why ionic componds have their properties
Highmelting point: ions are held together by strong electrostatic forces and it is hard to streck out
Brittle: crystal lattice structure off set and positive ions repel
Electrolyte: watersurrondion and separate ions move around carryelectricily
What is the structure of ionic compounds?
Crystal lattic where positive and negative attract
Define: electrolyte
Componddissolved in water and conducts electricity
Properties of molecular compounds
gls @room temp , no water dissolve, low boil point
When are atoms and ions most stable
Full octet
When are electrons must stable
Paired, bond pair or lone pair
What is the purpose of bondiing?
To achene a full/stable octet
Lewis theory of bonding
- a and I with full valance = stable
- Electron paired = stable
- Chemical bonds form to get full valance
- Mand nm = exchange ionic
- nm and nm = sharing covalent
Exception to octet rule
- Expand octet- extra e with central atom e.g. Sf6
2. Incomplete octet- notneed 8 electrons eg. Boron
What does vsepr
Valance shell electron pair repulsion
Predict molecule shape
E far as possible
Define:electronegativity
An atom’s ability toattract electron
What does a high en tell you?
The closer an atom will have to more to the other atom
Nonpolar covalent bond
Electrons are equally shared
0.0-0.4
Polarcovalent bond
Unequal sharingand havedipoles where electrons spend more time ones slightly neg and pos
0.5-1.6
Ionic bond (en)
Large en differencewhere a strong metal pulls electron from metal
1.7
Non-polar molecules
Bond dipoles cancel to zero
No localized charges
Polar molecule
Molecule with dipoles not equaling zero
Partially pos and neg
What are the 4 bond structures of solids
Ionic, metallic, moleular, covalent network
Ionic crystal
Metal cation and nonmetal anion
3d crystal lattic
Hold = Ionic bonds
Hard, brittle, electrolyte , high mp
Metallic crystal
Metals
Hold = electrostatic and free moving e
Shiny, conductive, malleable, ductile
Molecular crystal
Nm or molecular
Hold = intermolecular forces
Soft, not conductors
