Question

Predict which element in each of the following pairs is more electronegative according to the general trends in the periodic table: (a) Se or Br (b) \(C\) or \(B\) (c) Te or S (d) Ba or Be

Short answer

(a) Br is more electronegative; (b) C is more electronegative; (c) S is more electronegative; (d) Be is more electronegative.

Step-by-step solution

Understanding Electronegativity

Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons toward itself. In general, electronegativity increases across a period from left to right and decreases down a group in the periodic table.

Analyze Pair (a): Se or Br

Selenium (Se) and Bromine (Br) are both located in period 4 of the periodic table. Bromine is to the right of Selenium, which means it's more electronegative. Hence, Bromine (Br) is more electronegative than Selenium (Se).

Analyze Pair (b): C or B

Carbon (C) and Boron (B) are in the same period, period 2. Since Carbon is to the right of Boron, it is more electronegative. Therefore, Carbon (C) is more electronegative than Boron (B).

Analyze Pair (c): Te or S

Tellurium (Te) is in period 5, while Sulfur (S) is in period 3 on the periodic table. As you move down a group, electronegativity decreases, so Sulfur (S) is more electronegative than Tellurium (Te).

Analyze Pair (d): Ba or Be

Barium (Ba) is in group 2, period 6, whereas Beryllium (Be) is in group 2, period 2. Electronegativity decreases down a group, so Beryllium (Be) is more electronegative than Barium (Ba).

Key concepts

Periodic Table Trends

The periodic table is a powerful tool for understanding how elements behave chemically. One key trend in the periodic table is how electronegativity changes. Electronegativity is a measure of how strongly atoms can attract electrons in a bond. Across a period (from left to right), electronegativity generally increases. This is because elements tend to have more protons as you move to the right, which means they have a stronger positive charge to attract electrons. Along a group (from top to bottom), electronegativity decreases. Atoms have more electron shells as you move down, which means the outer electrons are further from the nucleus and feel less of its positive pull. These trends help predict how elements will react and bond with each other in chemical reactions.

Chemical Properties

Chemical properties refer to how a substance interacts with other substances. Electronegativity is a significant chemical property influencing how atoms form compounds. Elements with high electronegativity tend to attract electrons toward themselves when forming chemical bonds. This property is crucial in determining the type of bond that will form between atoms.

• Nonmetals, found on the right side of the periodic table, generally have higher electronegativity compared to metals.
• Electronegativity differences between atoms can lead to different types of bonds. A large difference often results in ionic bonds, while a smaller difference can lead to polar covalent bonds.

Understanding an element's electronegativity helps chemists predict how it will behave in a chemical reaction, what types of bonds it will form, and with which elements it will interact.

Atoms

Atoms are the basic units of matter. Each atom contains a nucleus composed of protons and neutrons, surrounded by electrons. The number of protons in the nucleus, also known as the atomic number, determines the identity of an atom and affects its chemical properties, including electronegativity.

• Electrons orbit at specific distances from the nucleus, known as energy levels or shells.
• The structure of these electrons affects an atom's ability to attract and hold onto electrons, influencing its electronegativity.

Atomic size can also affect how atoms interact. Smaller atoms with fewer electron shells can pull electrons more tightly due to a closer nucleus, often resulting in higher electronegativity.

Electron Affinity

Electron affinity measures the energy change when an electron is added to a neutral atom. Like electronegativity, it gives insight into an element's desire for electrons. When an electron is added and the energy released is high, the element has high electron affinity.
The periodic trends in electron affinity are similar to those in electronegativity:

• Across a period, electron affinity generally becomes more negative, showing greater attraction.
• Moving down a group, the electron affinity becomes less negative, indicating weaker attraction.

Understanding electron affinity helps in predicting chemical behavior, such as how readily an element will form negative ions, which is essential for understanding reactions and bond formations.