Physics Of The Mass Atomic Mass

964 Words Oct 7th, 2015 4 Pages
An atom contains protons, neutrons and electrons; the protons and neutrons are I the nucleus of the atoms and the electrons are in the outer shells of the atoms. There are different charges of protons, neutron’s and electron’s: protons have a positive charge however, neutron have no charges and electrons have a negative charge. The electron shells contain electrons a 8 electrons can make a full outer shell however, the first shell has to always be 2 electrons in it
In addition the periodic table is table that represents elements as symbols e.g. (He) represents helium, each symbol have a number above the symbols and one at the bottom of the symbols
The number at the top represents the relative atomic mass (protons plus neutrons) there is
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The F block contains radioactive elements.
Trends in chemical and physical properties in the groups and periods they belong to
I am going to explain the trends of chemical and physical properties by giving examples from group 1 and 7 elements, group 1 elements have similar properties as they are alkali metals and as you go down the group the elements get more reactive e.g. lithium is more harder and less reactive than the element at the bottom of the group which is the most reactive and very soft, also the melting points and The alkali metals generally become more dense going down the group and they become softer, but the trend is not perfect because potassium is less dense than sodium. All of the outer most shells in group 1 contain 1 electrons.

As you can see in the diagrams below lithium has a density of 0.53g/cm3 however as you go down the density increase e.g. sodium=0.917, potassium =0.862 etc. also the colours are all the same in the groups

Name: Lithium
Symbol: Li
Atomic Number: 3
Atomic Mass: 6.941 amu
Melting Point: 180.54 °C (453.69 K, 356.972 °F)
Boiling Point: 1347.0 °C (1620.15 K, 2456.6 °F)
Number of Protons/Electrons: 3
Number of Neutrons: 4
Crystal Structure: Cubic
Density @ 293 K: 0.53 g/cm3
Bentor, Yinon. Chemical Element.com - Lithium. Oct. 6, 2015 .
Colour: silvery

Name: Sodium

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