Answer:
Potassium
Explanation:
In group one of the periodic table both the melting and the boiling points usually decrease down the group.
Now, down the group, it's lithium that comes first, then sodium, then potassium.
Thus, among the 3, potassium is furthermost down the group by virtue of the factor it has the highest atomic number.
Therefore, we can say that potassium has the lowest boiling point among the 3.
Atomic number and the number of protons are the same...
Neutrons = Mass number - number of protons
Electrons are same # unless there is a charge
The whole number you see on the periodic table is the atomic number of the element which is also same as the number of protons
1) carbon - 14 ; Mass number = 14 , Protons = 6 , Neutrons = 14 - 6 = 8
Electrons = 6
2) Lead - 208 ; Mass # = 208 , Protons = 82 , Neutrons = 208 - 82 = 126
Electrons = 82
3) Uranium - 239 ; Mass # = 239 , Protons = 92,Neutrons = 239 - 92 = 147
Electrons = 92
4) Uranium - 238 ; Mass # = 238 , Protons = 92 , Neutrons = 238 - 92 = 146
Electrons = 92
5) Tin - 118 ; Mass # = 118 , Protons = 50 , Neutrons = 118 - 50 = 68
Electrons = 50
