- Protons And Neutons in Atom Nucleus
- Atomic Number = number of Protons.
- All Atoms of an Element have same amount protons.
- Mass Number = Protons No. + Neutron No.
- Isotope: Two or more forms of an element ,with different neutron numbers.
Relative Charge Relative Mass
Proton +1 1 Postive
Neutron 1 0 Neutral
Electron 1/1836 -1 Negative
- 1896,Dmitri Mendeleev arranged the element in this time in a table,in order of increasing mass(In Periods(Rows)).
- Placed elements with similar proporties in the same column (Groups).
- He left gaps in the table to allow elements to fit the patteren.
- Correctly predicted new elements would be discovered to fill the gaps.
- Was able to predict properties of these element by looking at properties ofelements surrounding the element.
- No. of Electrons = No. of Protons.
- The nearer the nucleus , low energy in the electrons.
- Electrons arrange in shells around the nucleus
- First shell can hold 2 electrons,Second and rest can hold 8 electrons.
- Electrons in the same group , have the same number of electrons in their outer shell
- Number of elements