Question

Using periodic trends, arrange the following atoms in order of increasing electronegativity. (a) B, C, H, Se, Si (b) \(\mathrm{C}, \mathrm{Ca}, \mathrm{Cl}, \mathrm{Cs}, \mathrm{Cu}\)

Short answer

Elements from set (a) arranged in order of increasing electronegativity are: B, Si, C, H, Se. Elements from set (b) arranged in order of increasing electronegativity are: Cs, Ca, Cu, C, Cl.

Step-by-step solution

Understanding Periodic Trends

Electronegativity is a measure of how strongly atoms can attract bonding electrons. The trend in the periodic table is such that electronegativity increases from left to right in a period and decreases from top to bottom in a group.

Arranging Elements from Set (a)

Using the mentioned trends, arrangement of elements from the set (a) i.e. B, C, H, Se, Si in order of increasing electronegativity is: B < Si < C < H < Se.

Arranging Elements from Set (b)

Applying the same principle, the elements from set (b) i.e. C, Ca, Cl, Cs, Cu can be arranged in order of increasing electronegativity as: Cs < Ca < Cu < C < Cl.

Key concepts

Electronegativity

Electronegativity is a fundamental chemical property that tells us how strongly an atom can attract electrons towards itself when it's part of a compound. It is an important concept because it helps predict how atoms will interact with each other to form molecules.

When looking at the periodic trends of electronegativity, the most electronegative elements are located in the top right corner of the periodic table, except for the noble gases, which do not commonly form compounds. As a rule of thumb, electronegativity increases as we move from left to right across a period, because atoms have more protons leading to a stronger attraction of electrons. Conversely, electronegativity decreases as we go down a group, due to the increased distance between the electron and the nucleus.

Understanding this property is crucial for determining the type of bond that will form between two atoms. In a bond between two atoms with a large difference in electronegativity, an ionic bond is likely to form. If the difference is small, the bond will be covalent, and the electrons will be shared more or less equally.

Periodic Table

The periodic table is a chart that organizes all the known chemical elements in an informative array that reflects recurring 'periodic' trends in their properties. Elements are arranged from left to right and top to bottom in order of increasing atomic number, which is the number of protons in an atom's nucleus.

The table is structured into rows called periods and columns known as groups or families. Elements within the same group have similar properties because they have the same number of electrons in their outermost shell. The layout of the periodic table allows us to predict a lot about an element's properties based on its position. For instance, metals are found on the left side and center, nonmetals on the right, and metalloids, which possess properties of both metals and nonmetals, are located along the stepping line between metals and nonmetals.

The organization of the periodic table reveals patterns that are helpful for chemists and students alike. For example, as you move across a period, elements tend to gain more protons and electrons and become less metallic. This layout is essential for understanding and predicting how different elements will behave and interact with each other.

Chemical Elements Ordering

Ordering chemical elements, especially when comparing their electronegativity, involves understanding their relative positions on the periodic table. This allows chemists to anticipate the behavior of atoms when they bond with others.

For example, in the exercise given, we had to arrange sets of elements in order of increasing electronegativity. Using the periodic trends, we know that elements on the left have a lower electronegativity compared to those on the right. Similarly, elements at the bottom of the table tend to have a lower electronegativity than those at the top.

Set (a), which includes B, C, H, Se, Si, can thus be ordered based on these trends. Boron (B) being on the left and selenium (Se) on a higher period, closer to the right side. Set (b) includes C, Ca, Cl, Cs, Cu and is a little trickier because it spans a wider range of groups. However, by knowing that cesium (Cs) is at the far left and chlorine (Cl) is at the far right of periods, we can confidently place them at the respective ends of the electronegativity scale. This ability to order elements based on their natural tendencies is crucial for predicting how they will react and is a key skill in the study of chemistry.