Chemistry - Chapter 1

schoolstudycanada's version from 2018-06-24 19:37

Section 1

Question Answer
DemocritusAtoms are smallest and indivisible
Daltons- Atoms can't be destroyed or subdivided
- atoms can't be created or destroyed
- Atoms of same element hve sa,e [rp[ertoes>?br- Atoms combine in special ratios when forming compounds
J ThompsonNegative Electrons float in a positively charged "pudding"
Rutherford- Atom is small
- Electrons orbit the nucleus randomly
- Nucleus made of neutrons and protons
- Nucleus makes up most of Atom mass
BohrElectrons orbits are in different levels
Electron Cloud ModelElectrons are found in clouds, and the probability of finding an electron within a certain area is based on it's energy level.

Section 2

Question Answer
Standard Atomic NotationMass (neutrons + protons) goes on top(NOT ATOMIC MASS)
->Element Symbol
Atomic Number (# of protons)

Also represented as ${ElementSymbol}-${Mass}
IsotopeSame of same #of protons but different amount of neutrons
Heavy WaterDeuterium (H-2). Used to absorb energy
Average Atomic MassWeighted mass of isotopes of element (Av = f1*m1+f2*m2...)
Periodic LawElements organised in groups share same properties.
Periodic Radius LawDecreases in size leading towards top right
Periodic Ionisation EnergyIncreases in value leading towards top right
Electron Affinity"How much (number) does it want electrons"
- Change in energy that occurs when electron is added to outer energy shell of an atom
Periodic Electron affinityIncreaces towards top right. Stop at group 7, ignores helium
Electronegativity"How much it wants the electrons (how close the electrons are kept)"
- Measure of attraction between atom and electron
- Tendency of an atom to attract electrons into a covalent bond (NOT RIPPING)
Periodic ElectronegativityIncreases toward top right

Section 3

Question Answer
Ionic BondElectrostatic attraction between opositekly charged ions
Ionic CompoundTwo oprositely charged ions bonded
Covalent BondAttraction between atoms that is created by sharign electrons
Molecular CompoundHeld together by covalent bounds.
- When bonding electrons rearrange to create octets
Bonding pairpair of shared electrons
Lone pairElectrons not shared
Polyatomic IonsMolecular compounds that have excess electrons

Section 4

Question Answer
How to find most stable lewis structuresCalculate formal charge of all strucutures provided. The one with mire zero charges is more stable
Formal ChargeNumber of valence electrons - Lone Electrons - Bonds

Section 5

Question Answer
Ionic vs Mollecular melting pointIonic have high melting point
Ionic vs Molecular conductivityIonic are electrolytes (acid and base are also electrolytes)
Intermolecular forcesForces between molecules (weaker than intramolecular)
Intramolecular forcesForces within molecules (stronger than intermolecular)
Melting point of Ionic compoundHigh melting point when:
- Large charge
- Small size
Melting point of molecular compounds- Type of force
- Size of molecule (atomic # * coefficient)
Types of Intermolecular forces- Dipole dipole
- H-Bond
- London/Dispersion forces
Dipole Dipole forcesFound in polar substances. It is the polarisation of the molecule which allows it to be attracted to other molecules
H-Bond forcesHydrogen bond
- Strongest type of dipole-dipole
- Occurs when Hydrogen bonds with OXYGEN, NITROGEN, FLOURINE~ (which are the most electronegative)
London/DispersionFound in non-polar
- Temporary polarisation of the molecule.
- VERY weak
- Stronger as molecular size increases
Electrical conductivity of ionic compoundsWhen ionic compound dissolves in water ions disassociate (separate).
- Ions are then free to move
Electrical conductivity of molecular compoundsWhen molecular compound dissolves, molecules separate BUT NO IONS PRODUCED
Why do things dissolve in water?Foreign particles are attracted to water molecules (due to the polarisation) and the foreign particle breaks apart.