Mass, Atomic Mass, Isotopes and Quantum Numbers

• Mass is the amount of matter in an object, measured in grams (g) or kilograms (kg).
• Atomic mass is the mass of a single atom of an element, expressed in atomic mass units (amu).
• Average mass is the average atomic mass of an element, considering the abundance of its isotopes.
• Isotopes of the same element have different numbers of neutrons, resulting in different masses.
• Carbon-12 has an atomic mass of 12 amu.
• Carbon-14 has an atomic mass of 14 amu.
• Hydrogen (H) has an atomic mass of 1.008 amu.
• Carbon (C) has an atomic mass of 12.01 amu.
• Oxygen (O) has an atomic mass of 16.00 amu.

Absorption (Excitation)

• When an electron absorbs energy, it "jumps" from a lower energy level to a higher energy level.

Emission (Relaxation)

• After an electron is excited to a higher energy state, it eventually falls back to a lower energy level and releases energy in the form of light or a photon.

Quantum Numbers

• Quantum numbers describe the properties of atomic orbitals and the electrons within them.

Principal Quantum Number (n)

• Relates to energy and size, with allowed values of 1 to infinity.
• Higher n values indicate that the electron is farther from the nucleus and has higher energy.
• n=1 means closest to the nucleus.
• n=2 means farther from the nucleus, with more energy.
• n can be any positive number.

Azimuthal Quantum Number (l)

• Indicates the shape of the electron's orbital, where:
• l = 0 is an s orbital;
• l = 1 is a p orbital;
• l = 2 is a d orbital;
• l = 3 is an f orbital.
• l can range from 0 to (n-1).
• If n=3, then l can be 0, 1, or 2, representing s, p, and d orbitals.

Magnetic Quantum Number (ml)

• Describes the orientation of the orbital in space.
• Value depends on l and can range from -l to +l.
• If l=2, ml can be -2, -1, 0, +1, +2.
• For each value of l, ml can take all values between -l and l.

Spin Quantum Number (ms)

• Electrons can spin in two possible directions: +1/2 (up) or -1/2 (down).
• No two electrons in the same orbital can have the same spin.
• ms can only be +1/2 or -1/2.

Electron Configuration

• Energy levels are n = 1, 2, 3, 4, 5...
• Higher the n, the farther the electrons are from the nucleus.
• Sublevels (orbitals) are s, p, d, and f.
• s holds 2e-
• p holds 6e-
• d holds 10e-
• f holds 14e-
• Determine the total number of electrons, equal to the number of protons, which equals the atomic number.
• Use the order of orbitals to fill electrons: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, etc.

Periodic Trends

• Ionization energy increases from bottom left to top right on the periodic table.
• Atomic radius increases from top right to bottom left on the periodic table.
• Effective nuclear charge (Zeff) increases from left to right on the periodic table.

Photon Energy and Light Calculations

• A photon is a particle of light that has energy but no mass; it is a "packet of light".
• λ = c / f (wavelength equals the speed of light divided by frequency).
• Where c is the speed of light, 3.00x10^8 m/s.
• E = h x f (energy equals Planck's constant times frequency).
• Where h is Planck's constant, 6.624x10^-34 J s.
• Wavelength is inversely proportional to frequency and energy.
• Increased wavelength entails decreased frequency and decreased energy.
• Decreased wavelength entails increased frequency and increased energy.
• Shorter wavelength corresponds to higher energy.
• Longer wavelength corresponds to lower energy.

Molar Conversions

• One mole contains 6.022 x 10^23 entities (Avogadro's number).
• 1mg = 10^-6 grams
• To convert from grams to moles, divide by molar mass.
• To convert masses to moles, divide by the molar mass.
• To convert between moles and number of atoms, use Avogadro's number.
• To convert between moles and volume, use 22.4L at STP.
• Example: The molar mass of H2O is 18.02 g/mol, meaning 1 mol of H2O weighs 18.02 grams.

Learn about mass, atomic mass, and isotopes. Explore the concept of average mass and how isotopes affect it. Understand absorption, emission, and quantum numbers.