IB Chemistry Topic 2-Atomic Structure

Position of protons in atom

inside of the nucleus

Position of neutrons in the atom

inside of the nucleus

Position of the electrons in the atom

spinning around outside the nucleus

Relative mass of proton

1 amu

Relative mass of neutron

1 amu

Relative mass of electron

1/1836 amu

What is the atomic number

The atomic number is the number of protons in the atom. This is given the symbol Z

What is the mass number

The mass number is the total mass of an atom, or; the sum of its protons and neutrons. It is given the symbol A.

isotopes

atoms with the same number of protons but different numbers of neutrons

isotope symbol notation

chemical properties of isotopes

the chemical properties of all isotopes are the same as their base elements because chemical properties are based on the outer electrons and isotopes of an element have the same number of electrons

physical properties of electrons

there are small differences in the physical properties of isotopes, allowing them to be separated apart from each other, such as with uranium (different weights of the isotopes is used to separate)

Uses of isotopes

Breaking down of many isotopes emits radiation. This radiation can be used for sterilization, dating of artifacts, nuclear power and many other things

use of mass spectrometer

a tool used to determine the masses of individual isotopes

mass spectrometer diagram STUDY THIS

Mass spectrometer step 1: Injection

sample is injected into the ionization chamber

Mass spectrometer step 2: vaporization

It is vaporised and the gas streams into the ionisation chamber

Mass spectrometer step 3: ionization

The electron beam knocks an electron off the vaporised particles makong positive ions

Mass spectrometer step 4: acceleration

The positive ions are attracted towards the accelerating plates

Mass spectrometer step 5: deflection

The magnetic field deflects the lighter ions more than the heavy ions

Mass spectrometer step 6: detection

As the magnetic field is varied by the controller, ions with different masses are detected - these are recorded on the mass spectrum.

Calculating relative abundance of an isotope with a mass spectrometer

Add all the results of the test and then divide one of the results by the sum of all of them to find that isotopes relative abundance

Calculating relative atomic mass of an element

relative atomic mass = (isotope 1's mass × isotope 1's relative abundance) + (isotope 2's mass × isotope 2's relative abundance) and so on then divide by 100

Why do different elements burn different colors

because when the gaseous ions are given energy they emit different types of electromagnetic radiation

velocity of travel for electromagnetic waves

c (meters second⁻¹) = λ (meters) × f (second)⁻¹

where c is the velocity of travel, λ is the wavelength and f is the frequency

The energy of electromagnetic radiotion

E (joules) = h (Joules seconds) × f ( s⁻¹)

where E is energy, h is Planck's constant and f is frequency

Planck's constant value

6.63 x 10⁻³⁴ (J s)

electromagnetic spectrum

Continuous spectrum

Results when gas pressure is higher and the atoms collide a lot so all the lines are smeared together

Emission spectrum

produced by thin gases in which the atoms do not experience many collisions

absorption spectrum

An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies

What does it mean when an electron relaxes?

It falls back to its previous energy shell

What does it mean when an electron is promoted

Due to an increase in energy it jumps up to a higher energy shell (known as being in its excited state)

Definition of electron transitions

the movement of electrons between the shells

Explain how energy is created during electron transitions

when electrons jump between shells they releases energy if they go down in shells (in the form of a quantum) The farther down they drop the more energy they release. This amount of energy directly relates to lines on an emission spectra