The mass number = protons + neutrons = 56
The atomic number = number of protons = 26
Therefore the number of neutrons = 56-26 = 30
Isotopes are atoms of the same element with different mass numbers (atoms of the same element must contain the same number of protons, but can contain a different number of neutrons)
Be able to identify protons, neutrons and electrons in isotopes and in ions.
For a given element the number of protons never changes
The number of neutrons depends on the mass number of the isotope in question
The number of electrons is the same as the number of protons UNLESS we are dealing with an ion!
Compare properties of isotopes of an element
Since the isotopes of an element have the same arrangement of electrons, their chemical properties are identical.
The physical properties of the isotopes of an element differ due to their different in mass.
Boiling point, melting point, etc.
Describe and explain the operation of a mass spectrometer and how it may be used to determine mass and relative abundance of atoms and their isotopes.
A vaporized sample is injected into the mass spectrometer.
This sample is ionized by bombarding it with high-energy electrons.
The positive ions are accelerated by an electric field.
The positive ions are deflected by a magnetic field.
The ions are detected by producing a current.
Calculate average atomic mass from isotopes and relative abundance.
For elements, which have more than one isotope (the majority), the measured relative atomic mass of a sample will be the average mass of all the isotopes in the sample.
Describe the electromagnetic spectrum and the relative energy associated with each component
c = λƒ
c = speed of light; λ = wavelength; ƒ = frequency
E = hƒ
E = energy; h = Planck’s constant (6.63 x 10-34 J s-1)
↓ λ = ↑ ƒ = ↑ E
Explain how a bright line spectrum is connected to the position of electrons around the nucleus.
Describe the basic tenets of the current model for the atom: the quantum mechanical model
Know and explain the four quantum numbers. [HL]
1. Energy Level
2. Subshell
3. Orbitals
4. Spin
Identify and explain the changes in first ionization energy for the existence of energy levels and sublevels. [HL]
S subshell: 1 orbital – 1st subshell – 2 electrons
P subshell: 3 orbital’s – 2nd subshell – 6 electrons
D subshell: 5 orbital’s – 3rd subshell – 10 electrons
F subshell: 7 orbital’s – 4th subshell – 14 electrons
Apply the Aufbau principle, Hund's Rule and Pauli Exclusion Principle for the location of electrons.
Aufbau principle: Used to determine the electron configuration of an atom. Build up.
Hund’s Rule: Hotel game. Everybody gets his or her own room, then you double up.
Pauli’s Exclusion Principle: Has to do with electron configuration. Opposite spin.