Element of life 3 & 4

Question 1

What is the principle quantum number? n how many electrons can the shell have

Answer 1

1. the higher the value, the higher the energy
2. n = 2 electrons
   n = 8 electrons
   n = 18 electrons
   n = 32 electrons

Question 2

The different types of sub-shells can hold different numbers of electrons:

Answer 2

1. n=1 1s^2
2. n=2 2s^2 2p^6
3. n=3 3s^2 3p^6 3d^10
4. n=4 4s^2 4p^6 4d^10 4f^14

Question 3

what is the order of the sub-shells ?

Answer 3

s, p, d, and f

Question 4

what are the shapes of :
1. s-orbitals
2. p-orbitals

Answer 4

1. s- orbitals = spherical
2. p-orbitals = 3”8” x, y+z axes

Question 5

When there is more than one orbital with the same energy, these are first filled singly by electrons. why is this ?

Answer 5

• keeps electrons as far apart as possible, minimising repulsion
• uses smallest amount of energy possible

Question 6

when is it correct that energy of 3d > energy of 4s ?

Answer 6

period 3 elements and up to nickel in period 4

Question 7

whats is the configuration of 1. calcium and 2. gallium ?

Answer 7

1. calcium = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2
2. gallium = 1s^2 2s^2 2s^5 3s^2 3p^6 3d^10 4s^2 4p^1

Question 8

how does the modern periodic table group elements arranged ?

Answer 8

• Groups element sin order of increasing atomic number and according to their commin propertie

Question 9

How did Mendeleev predicted the periodic ?

Answer 9

• left gap in his table of elements
• used increasing mass number

Question 10

which row is the s-block, d-block, p-block and f-block ?

Answer 10

1. s-block = 1 to 2 metal elements
2. d-block = transition elements
3. p-block = 3-6 nonmetals elements
4. f-block = remaining

Question 11

How can you deduce an elements electron configuration from the periodic table?

Answer 11

• period: outer shell number
• group : number of e- in outer subshell

Question 12

what trend do melting/boiling points follow across period ?

Answer 12

• Melting point increases then decreases across the period
• This is because the metals on the left-hand side of a period are metalically bonded so have higher melting points due to the deloclaised electrons between nuclei. The further across the period, the more electrons and the more positive the nucleus becomes, so the stronger the bonds.
• Silicone has a high melting point because it is a giant covalent structure which requires a lot of energy to break
• The remaining non-metals are simple molecules. They are only held together by weak intermolecular forces (e.g. id-id). The melt these molecule you don’t need to break the strong covalent bonds, only the weak intermolecular bonds.

Question 13

Which of these elements are in the same group ?

Answer 13

A,C,E

Question 14

Describe the periodicity of melting points in period 2 and 3 :

Answer 14

period 2 :
* melting poinjt increases up to C then falls dramatically from C to N
* intermolecular bonds in nitrogen much weaker than in carbon
period 3:
* Melting point increases up to Si then falls dramatically from Si to P
* intermolecular bonds in phosphorous much weaker than in silicon

Question 15

Explain how the Geiger-Marsden experiement provided evidence for a small, dense nucleus:

Answer 15

• Alpha particle beam fired at thin sheet of gold foil. expected to passs through or be slightly deflected
• very few deflected at all which means that most of atom is empty space
• small number deflected backwards concluding that most of atom’s mass is concentrated in a small nucleus, which is +ve since it repelled +ve particles