Sticky Notes Sticky Notes

IB Chemistry HL

by
EJ
Electronegativity

March 13, 2025

A measure of the ability of an atom to attract electrons in a covalent bond.

OIL RIG

March 13, 2025

- Oxidation is the loss of electrons + addition of oxygen, removal of hydrogen, increase in oxidation state.

- Reduction is the gain of electrons + removal of oxygen, addition of hydrogen, decrease in oxidation state

Ligands

March 13, 2025

- A species that uses a lone pair of electrons to form a coordination bond with a metal ion.
Charges of ligands are in data booklet
- H20 and NH3 -> Neutral atom (0 charge)
- Cl, CN, and OH -> -1 charge

IR Active

March 13, 2025

A bond in a diatomic molecule only interacts with IR if it is polar. Non-polar diatomic molecules will not absorb the radiation.

Kelvin and Celsius

March 13, 2025

1 degree change in Kelvin = 1 degree change in celsius

Enthalphy Change Percision

March 13, 2025

The precision of temperature measurements limits the accuracy of the answer.
The actual value may be lower than the estimate due to heat loss and incomplete combustion.

Ferromagnetics

March 15, 2025

Iron, cobalt and nickel.
Have unpaired electron in d orbitals leading to net magnetic moment.

Electronic Configuration Exception

March 19, 2025

Chromium
[Ar] 3d⁵ 4s¹

Copper
[Ar] 4s¹ 3d¹⁰

Melting Point Trends

March 19, 2025

Across the period -> Bonding
- Increases for metals (More delocalized electrons per atom + Higher charge density → stronger metallic bonding).
- Peaks at Group 4 (giant covalent structures).
- Decreases for non-metals (weak london dispersal forces ).

Down the group:
- Metals decrease as atomic size increases -> increases the distance between the nucleus and delocalized electrons -> weaker attraction.
- Non-metals increase as larger atoms → more electrons → stronger temporary dipoles.

Atomic Radius Trend

March 19, 2025

Across a Period → Atomic Radius Decreases
Increasing Nuclear Charge: More protons → stronger attraction between nucleus and electrons.
Same Energy Level: Electrons are added to the same shell, so shielding remains nearly constant.

Down a Group → Atomic Radius Increases
More Electron Shells: Each period adds a new energy level → outer electrons are farther from the nucleus.
Increased Shielding: Inner electrons block nuclear attraction → weaker pull on outer electrons.

Metal -> Metalloids - > Nonmetals

March 20, 2025

Metals are located on left side/center of periodic table; exhibit:
High electrical/thermal conductivity
Malleability/ductility
Metallic luster

Nonmetals found on right side of periodic table; characterized by:
High electronegativity
Poor electrical/thermal conductivity

Metalloids found along diagonal line between metals/nonmetals:
Display intermediate properties
Share characteristics of both metals and nonmetals

Charge Density

March 20, 2025

Smaller ions have a higher charge density -> a stronger electrostatic attraction

- Higher charge density means greater attraction to water molecules, producing more exothermic hydration energy.

Metalloid

March 20, 2025

Physical properties:
Metallic lustre
Moderate electrical conductivity (less than metals)
High melting point

Chemical Properties:
Form Amphoteric Oxide

Homologous Series

March 20, 2025

same general formula;
successive members differ by CH2
similar chemical properties;
gradual change in physical properties;
same functional group;

Mass Spectrometry

March 20, 2025

TMS has the formula (CH3)4Si is used as the reference compound in NMR spectroscopy so a single sharp peak at exactly δ = 0 ppm