3.1.3 Apply the relationship in between the electron arrangement of elements and their position in the Periodic Table up to Z = 20.

The position of an element is related to the electron arrangement in the atom.

• The period number represents how many shells it has. 
• The group number represents how many valence electron(s) the atom contains.

example) Sodium

• period 3 - sodium has 3 occupied energy levels, (shells).
• group 1 - one electron in the outer shell. 

3.1.2 Distinguish between the terms group and period.

groups - columns of the periodic table

periods - rows of the periodic table 

Groups are numbered from 1 to 7. The gap between group 2 and group 3 is filled by transition elements from the fourth period and onwards. 

3.1.1 Describe the arrangement of elements in the Periodic Table in order of increasing atomic number.

Elements are placed in order of increasing atomic number (Z). Which is the number of protons in the nucleus of the atom. 

2.3.4 Deduce the electron arrangement for the atoms and ions up to Z=20.

Element	Electronic arrangement	Element	Electronic arrangement
Hydrogen	1	Sodium	2,8,1
Helium	2	Magnesium	2,8,2
Lithium	2,1	Aluminum	2,8,3
Beryllium	2,2	Silicon	2,8,4
Boron	2,3	Phosphorus	2,8,5
Carbon	2,4	Sulfur	2,8,6
Nitrogen	2,5	Chlorine	2,8,7
Oxygen	2,6	Argon	2,8,8
Fluorine	2,7	Potassium	2,8,8,1
Neon	2,8	Calcium	2,8,8,2

2.3.3 Explain how the lines in the emission spectrum of hydrogen are related to electron energy levels.

The movement of electrons between the shells is called electron transitions.

The emission and absorption spectra are both the result of electron transitions, they can be used like bar codes to identify the different elements.

When electron transitions take place the energy emitted can be detected and its wavelength measured. This provides information about the relative energies of the energy shell.

One packet of energy or photon is released for each electron transition.

image and the following  information from http://eilat.sci.brooklyn.cuny.edu/cis1_5/Old%20HWs/HW2d_C.htm

Electrons in their shells can receive energy in the form of heat or electricity and jump to higher energy shells (promotion). They cannot remain at these higher levels (excited state) for very long and soon fall back to their original shell (or other shells). When they fall back (relax) they have to lose the energy difference between the two shells. his loss of energy is performed by releasing electromagnetic energy in the form of infrared, visible light or ultraviolet radiation.

In the hydrogen atom (the simplest case with only one electron to 'jump' between shells) the energy emitted appears in several series of lines each series corresponding to electrons falling back to different levels. This is shown in the diagram below.

The Lyman series corresponds to transitions between the higher shells and the lowest shell (ground state).

The energy shells are usually given a letter 'n' to describe the specific energy level. The lowest level is n=1 the second level is n=2 etc.

Transitions from higher shells (n >2) to n=2 produce radiation in the visible region of the spectrum and we can actually see it by splitting the light using a prism or diffraction grating and projecting it onto a screen. 

When an electron falls from a lower to a higher energy level, energy is absorbed and a line in the absorption spectrum is produced. 

When an electron falls from a higher to a lower energy level radiation is given out by the atom and a line in the emission spectrum is produced.

When an atom is at the highest energy n=∞, it is no longer in the atom, it has been ionized. 

Ionization energy - energy needed to remove an electron from the ground state of each atom in a mole of gaseous atoms.

2.3.2 Distinguish between a continuous spectrum and a line spectrum.

Continuous spectrum - produced when white light passes through a spectrum. It shows all the frequencies.

Line spectrum - produced when white light passes through hydrogen gas, it shows selected line frequencies. An absorption spectrum is produced.

• If high voltage is applied to the gas, an emission spectrum is produced.
• Colors in the emission spectra are missing from the absorption spectra.

2.3.1 Describe the electromagnetic spectrum.

• electromagnetic radiation comes in different forms of different energy

• all electromagnetic waves have the same speed but we can tell them apart by their wave lengths 

• different colors of visible light also have different wavelengths 

• frequency - number of waves which pass a particular point in one second

• the shorter the wavelength the higher the frequency 

• speed = frequency x wavelength