Trends in the Periodic Table Atomic Size Metallic Character - UNSOLVED PRACTICE SET

Q7. Why does atomic size decrease across a period from left to right?

Q8. Why does metallic character decrease across a period?

Q9. Arrange the following elements in increasing order of atomic size: F, O, N, C. Give a reason for your answer. 

Q10. Why is sodium more metallic than magnesium, even though both are in Period 3?

Q11. Your elder brother explains that gold jewellery is made of a metal that doesn't rust easily, while iron gates in your school rust quickly. Using the concept of metallic character, explain why some metals are more reactive (more metallic) than others.

Q12. Why does chlorine have a smaller atomic size than sodium, even though both are in the same period?

Q13. Explain the trends in atomic size across a period and down a group. Use the examples of Period 2 elements (Li to Ne) and Group 1 elements (Li to K) to illustrate your answer. Why does atomic size not strictly follow the trend in some cases?

Q14. Describe the trend in metallic character across a period and down a group. Explain:

(a) Why metallic character decreases from left to right across a period

(b) Why metallic character increases down a group

(c) Why non-metals are found on the right side of the periodic table

(d) Why the dividing line between metals and non-metals runs diagonally

Illustrate with suitable examples.

Q15. During a visit to a science museum, you see a display showing the relative sizes of atoms from different groups and periods.

(a) If you compare a sodium atom (Group 1, Period 3) with a potassium atom (Group 1, Period 4), which would be larger? Why?

(b) If you compare a sodium atom with a chlorine atom (Group 17, Period 3), which would be larger? Why?

(c) Your teacher asks you to predict which element between aluminium (Period 3) and gallium (Period 4) would be more metallic. Explain your reasoning.

(d) Why do elements at the bottom left of the periodic table (like caesium and francium) have the largest atomic sizes and highest metallic character?

Q16. The atomic radii of some Period 3 elements are given below:

Table

Element Na Mg Al Si P S Cl

Atomic Radius (pm) 186 160 143 118 110 104 99

(a) Plot a graph of atomic radius vs. atomic number for these elements.

(b) What trend do you observe? Explain the reason behind this trend.

(c) Predict the approximate atomic radius of argon (Ar, Z=18). Would it be larger or smaller than chlorine? Explain.

Q17. The metallic character of elements can be measured by their tendency to lose electrons (ionization energy).

(a) If the ionization energy of sodium is 496 kJ/mol and magnesium is 738 kJ/mol, which element is more metallic? Explain.

(b) The ionization energy of potassium is 419 kJ/mol. Compare its metallic character with sodium and explain why it differs.

(c) Arrange Na, Mg, and K in decreasing order of metallic character. Justify your arrangement.

Q18. A student is comparing two elements X and Y:

Element X is in Period 2, Group 14

Element Y is in Period 3, Group 14

(a) Identify elements X and Y.

(b) Which element would have a larger atomic size? Explain using the concept of electron shells.

(c) Which element would be more metallic? Explain your reasoning.

(d) If element Z is in Period 3, Group 17, compare its atomic size with X and Y. Arrange all three in increasing order of atomic size.