Lewis structures
Valence electrons
Which electrons do we count for Lewis structures
2 bonding and 2 non bonding regions of electron density or 2 bonding and 1 non bonding
How many regions of electron density does a bent molecule have?
Delocalised electrons or free moving ions
What is required in order for a substance to conduct electricity?
Endothermic
What is the word for absorbs heat? or bond braking is always this?
Used to calculate number of moles.
What is n=m/M used for?
Bonding electrons
Which electrons do we put into Lewis structures first?
A bond angle of 120
What is the bond angle of trigonal planar and some bent shapes?
Covalent network 2d
What type of solid is graphite
Exothermic
What is the word for absorbs heat? or Bond making is always this?
Repel for maximum separation and to minimise repulsion
What do regions of electron density do?
8 apart from H, Be and B
How many valence electrons do atoms need a share of?
A bond angle of 180
What is the bond angle of a linear molecule?
Weak intermolecular bonds
Why are molecular solids soft with low melting and boiling points?
Delta H
What symbol is used for change in enthalpy?
Uneven sharing of electrons
What is electronegativity? or What causes polar bonds?
Move electrons to form a double bond/s or even triple bonds
What should you do if the atoms in your Lewis structure do not contain a share of 8 electrons
Trigonal planar
What shape has 3 bonding regions and 0 non bonding regions?
A 3D lattice with alternating cations and anions held strongly in place
Why are ionic substances brittle?
Steam condensing
What is an example of an exothermic reaction?
Use the idea of which atom in the molecule can form the most bonds.
How do you determine the central atom for a Lewis structure?
Hydrogen, Beryllium, Boron
Which atoms can share a maximum of 2, 4 and 6 electrons?
A bond angle of aprox 109
What is the bond angle of tetrahedral, (some) bent and trigonal pyramid shapes?
Graphite has delocalised valence electrons between layers and diamond has no free moving charged particles or ions
Why does graphite conduct electricity and diamond does not?
Using bond energies to calculate delta H
What does delta H = (sum of bonds breaking) - (sum of bonds forming) show?
An ionic polar substance dissolving in water (diagram required)
What does this diagram represent? (Diagram showing water and cation/ anion dipole interactions required)