Periodic Trends | Chemistry for Grade 11 (IGCSE) PDF Download

The Metallic Character of Elements

• As you progress across a Period on the Periodic Table from left to right, the metallic character of elements diminishes, while it increases when moving down a Group.
• This trend arises because atoms have a greater tendency to accept electrons to achieve a full valence shell rather than losing them to attain a full outer shell.
• Metals are situated on the left side of the Periodic Table, whereas non-metals occupy the right side.
• Positioned between metals and non-metals are elements that exhibit characteristics of both, known as metalloids or semi-metals.

Properties of metals and non-metals

Periodic Trends & Electronic Configuration

• The arrangement of electrons into shells for an atom is known as the electronic configuration. For instance, the electronic configuration of carbon is 2,4.
• There exists a correlation between the electronic configuration of elements and their positions on the Periodic Table.
• The number of notations in the electronic configuration indicates the number of occupied electron shells of the atom, which in turn reveals the period.
• The last notation in the electronic configuration signifies the number of outer electrons the atom possesses, indicating the group number.

Example: Electronic configuration of chlorine:

The electronic configuration of chlorine:

• The red numbers at the bottom indicate 3 shells of electrons for a chlorine atom.
• The final notation of 7 signifies 7 outer electrons, placing chlorine in Group VII.

The Position of Chlorine on the Periodic Table:

Elements in the Same Group

• Elements in the same group exhibit similar chemical properties due to their outermost electrons interacting.
• Similarity in properties arises from having the same number of electrons in the outer shell.
• Lithium and sodium, both in Group I, can form compounds by donating electrons to elements in Group VII.
• Down a group, each subsequent element adds a full shell of electrons.
• Lithium's electronic configuration: 2,1
• Sodium's electronic configuration: 2,8,1
• Potassium's electronic configuration: 2,8,8,1

Predicting Properties

• The arrangement of elements on the Periodic Table reflects patterns in both their chemical behavior and physical properties.
• These trends manifest both vertically down groups and horizontally across periods.
• Utilizing the Periodic Table enables the prediction of various properties like boiling point, melting point, density, and reactivity.
• Some notable trends include the rapid reactivity of Group I elements with water, the inertness of noble gases, and the higher density of transition elements compared to Group I elements.
• Reactivity diminishes down Group VII, while melting point decreases down Group I.
• Consequently, the Periodic Table serves as a tool for anticipating the behavior of specific elements.

Identifying Trends

• By analyzing information about elements, we can recognize patterns in their properties.
• For instance, this analysis helps us determine how the reactivity of Group I metals changes.
• Below is a summary of the reactions of the initial three Group I elements with water.
• Observations of Lithium, Sodium, and Potassium with Water:

• The observations indicate that the reactivity of Group I metals increases as we move down the group.
• This information allows us to anticipate the trend for rubidium, caesium, and francium as we progress down Group I.
• As alkali metals become more reactive down the group, rubidium, caesium, and francium exhibit more vigorous reactions with air and water compared to lithium, sodium, and potassium.
• Among these metals, lithium is the least reactive at the top, while francium is the most reactive at the bottom.
• Due to its rarity and radioactivity, confirming predictions related to francium can be challenging.

Table to Show the Predicted Reaction of other Group I Elements with Water