atomic structure - work sheet

Answer the following
1. The smallest repeating unit of an element is called-----------------
2. Central of the atom is called---------------------
3. Name the three particles in side the atom
4. Name the negative particle in side the atom ---------------------
5. Name the positive particle inside the atom --------------------------
6. Name the path of the electron around the nucleus------------------------
7. The number of --------------------------and------------------------particles are same in
inside the atom
Try to answer the following
1.Why the atom is neutral?
2.Define mass number.
3. Define atomic number
4. Define isotopes
5.why isotopes have similar properties
6.which one of the following are isotopes
35 37 37 35
Cl , Cl , Cl , Cl
17 16 17 16
7.Draw the electron arrangement in
Magnesium, calcium , sodium, lithium, sulphur
8.Relative atomic mass of an elementUse relative mass of isotopes and their relative abundance. E.g. Chlorine has two isotopes with mass numbers 35 and 37. 35 37 75% is Cl and 25% is Cl 17 17 Let there be 100 atoms Total mass of 100 atoms = (75 * 35) + (25 * 37) = 3550 Average mass of an atom (relative atomic mass of chlorine) = Total mass /Number of atoms =3550/100 so relative atomic mass of chlorine = 35.5
Task
1. Bromine exists as two isotopes with mass numbers 81 and 79. If there is 50% of each isotope in a sample what is the relative atomic mass of bromine?
2. Calculate the relative atomic mass of the following:
(a) gallium 60% Ga 69 and 40% Ga 71
(b) neon 90% Ne 20 and 10% Ne 22
(c) silver 50% Ag 107 and 50% Ag 109
(d) boron 20% B 10 and 80% B 11