Questions on chapter 3

3.1 The Periodic Table

1. What are groups and periods in the periodic table ?

2. Which elements are alkaline earth metals and what ions do the form ?

3. Which elements are halogens and what ions do they form ?

4. Which elements are noble gases and what ions do they form ?

5. Which elements are alkali metals and what ions do they form ?

6. Which elements are metals, semi-metals (metalloids) and non-metals ?

3.2 Physical Properties

7. What is nuclear charge and effective nuclear charge ?

8. What is the electrical conductivity ? How does it change in the periodic table ? Why does it change like that ?

9. What is the radius ? How does it change in the periodic table ? Why does it change like that ?

10. What is the ionic radius ? How does it change in the periodic table ? Why does it change like that ?

11. What is the ionisation energy ? How does it change in the periodic table ? Why does it change like that ?

12. What is the electronegativity ? How does it change in the periodic table ? Why does it change like that ?

13. What are melting and boiling points ? How do they change in the periodic table ? Why does it change like that ?

14. Make a summary picture of how thing changes.

15. How do things change for alkali metals ?

16. How do things change for halogens ?

17. How do things change in period 3 ?

3.3 Chemical Properties

18. What happens if one mix alkali metals with water ?

19. What happens if one mix alkali metals with halogens ?

20. What happens if one mix alkali metals with oxygen ?

21. What happens if one mix alkaline earth metals with water ?

22. What happens if one mix alkaline earth metals with halogens ?

23. What happens if one mix alkaline earth metals with oxygen ?

24. What happens if one mix a halogen with silver ions ?

25. What happens if one mix a halogen with halide ions ?

26. What happens if one mix a halogen with water ?

27. What happens if one mix a halogen with oxygen ?

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Elements increase in atomic number across each period, and down each group.
Group – the columns going down = number of valence electrons in the atom.
Period – the rows going across = number of main electron shells…s, p , d and f blocks.

Reactions of elements in the same group are similar because they have identical outer shells (ie same number of valence electrons).

Alkaline earth metals:Be, Mg, Ca....Be²⁺ Mg²⁺, Ca²⁺....

Halogens:F₂, Cl₂, Br₂, I₂..... F^-, Cl^-, Br^-, I^-.......

Noble gases: Ne, Ar, Kr, Xe ..... no ions

Alkali metals: Li, Na, K....Li⁺, Na⁺, K⁺....

Nuclear charge = Z = the number of protons.
The electrons in the inner shells shield the electrons in the outer shells so the effective charge that these electrons experience is less than Z.

Li->Cs (down the alkali metals)

Atomic and ionic radius increases due to increased electron shielding. The outer electron is in an energy level that is progressively further away from the center of the nucleus.

Ionisation energy decreases due to increased electron shielding.

Melting/boiling point decreases due to increased electron shielding (hence decreased forces).

Electronegativity decreases due to increased shielding (hence decreased attraction for outer electrons).

F->I (Down the halogens)

Atomic and ionic radius increases due to increased electron shielding.

Ionisation energy decreases due to increased electron shielding.

Melting/boiling point increases due to increased number of electrons->increased london dispersion forces.

Electronegativity decreases due to increased shielding -> decreased attraction for outer electrons.

Na->Ar (across period 3)

Atomic radius decreases due to increased nuclear charge -> greater attraction for electrons.

Ionic radius decreases Na->Al (due to increased nuclear charge) jumps Al->Si (due to reversal of ionisation direction…increased electron-electron repulsion) decreases Si->Ar (due to increased nuclear charge).

Ionisation energy increases due to increased nuclear charge.

Melting/boiling point increases Na->Si (due to stronger metallic bonding – more delocalized electrons then network covalent) drops Si-P (due to network->molecular covalent) increases P->S (due to increased LDF between molecules i.e. P₄, S₈). Drops to Cl, due to smaller molecules (Cl₂) decreases to Ar (individual atoms->fewer electrons->smaller LDF).

Electronegativity increases due to increased nuclear charge -> greater attraction for electrons.