IB MYP Integrated Science- Chemistry- Trends, periods, groups-Study Notes - New Syllabus

Periodic Table (Trends, Periods, and Groups)

The periodic table is a systematic arrangement of elements in order of increasing atomic number. It allows scientists to identify patterns (trends) in properties and predict the behavior of elements.

Structure of the Periodic Table

The periodic table is organised into periods (horizontal rows) and groups (vertical columns).

Periods

• Horizontal rows in the periodic table
• Elements in the same period have the same number of electron shells
• Atomic number increases from left to right

Groups

• Vertical columns in the periodic table
• Elements in the same group have the same number of valence electrons
• Similar chemical properties and reactivity

Key Groups

• Group 1: Alkali metals (very reactive metals)
• Group 7: Halogens (reactive non-metals)
• Group 0/18: Noble gases (very unreactive)

Trends Across a Period

As you move from left to right across a period:

• Atomic number increases
• Number of valence electrons increases
• Atomic radius decreases
• Reactivity of metals decreases, non-metals increases

Trends Down a Group

As you move down a group:

• Number of shells increases
• Atomic radius increases
• Reactivity changes depending on group

Group Trends Examples

Group 1 (Alkali Metals)

• Reactivity increases down the group
• Atoms lose electrons more easily

Group 7 (Halogens)

• Reactivity decreases down the group
• Atoms gain electrons less easily

Group 0 (Noble Gases)

• Very low reactivity
• Full outer electron shell

Link to Electron Configuration

• Group number → number of valence electrons
• Period number → number of electron shells

Metals and Non-Metals

• Metals are on the left side
• Non-metals are on the right side
• Metalloids lie in between

Real-World Importance

• Predicting reactivity of elements
• Designing materials and chemicals
• Understanding chemical behavior in industry and biology