This document discusses trends in properties of elements within the periodic table. It covers which period chromium is in, which element has a valency of 3, the electron configuration of magnesium, the type of bonding in magnesium chloride, the chemical formula of barium oxide, what governs the boiling point of halogens, and periodic trends in ionization energy and atomic radius. It also mentions which atoms buck the general trend of ionization energies and asks which of the options are periodic trends in atomic radius.

1. Patterns and Trends
in properties of
elements
CHE-3004A – Lecture 5

2. Learning objectives
Elements are arranged in order of increasing atomic number in
the Periodic Table (not mass! Eg Ar and K).
Elements in the same group have similar properties.
Trends in properties of elements within Groups
for example 1, 2, 17.
Periodicity of properties of elements.

3. What period is chromium, Cr, in?
A. Two
B. Three
C. Four
D. Five

4. Which of these elements has a
valency of 3?
A. Aluminium
B. Nitrogen
C. Scandium
D. Yttrium

5. 1s22s22p63s1 is the sub-shell level
electron configuration of which atom?
A. Magnesium
B. Potassium
C. Fluorine
D. Sodium

6. What sort of bonding is present
in magnesium chloride?
A. Metallic
B. Covalent
C. Ionic
D. Amphoteric

7. What is the chemical formula of
barium oxide?
A. BaO
B. Ba2O
C. BaO2
D. Ba2O3

8. What governs the boiling point
of the halogens?
A. Covalent bond
strength
B. Intermolecular
interactions
C. Ionic bonding
D. Metallic bonding

9. Cl2 + 2 KF → 2 KCl + F2
A. True
B. False

10. Which of these are periodic
trends in ionisation energy?
A. Ionisation energy
increases across a
period.
B. Ionisation energy
decreases down a
group.
C. Ionisation energy
increases with atomic
number.
D. Ionisation energy
increases with effective
nuclear charge.

11. Which atoms have ionisation energies
that buck the general trend?

12. Which of these are periodic
trends in atomic radius?
A. Atomic radius decreases
across a period.
B. Atomic radius increases
down a group.
C. Atomic radius decreases
with atomic number.
D. Atomic radius decreases
with effective nuclear
charge.