Learning Lab

Predict which atom is larger for the following pairs of atoms:
(a) \(\ce{C}\) and \(\ce{F}\)
(b) \(\ce{Na}\) and \(\ce{Cs}\)
(c) \(\ce{Sc}\) and \(\ce{Ni}\)

Answer

Each atom’s position in the periodic table and atomic number can be used to predict its atomic size.
(a) \(\ce{C}\) (\(Z=6\)) and \(\ce{F}\) (\(Z=9\)) are located in the second period. When moving across a period from left to right atomic radii decrease as a result of increasing Z. \(\ce{C}\) lies to the left of \(\ce{F}\) in the same row. Therefore, \(\ce{C}\) is larger than \(\ce{F}\).
(b) \(\ce{Na}\) (\(Z=11\)) and \(\ce{Cs}\) (\(Z=55\)) are located in group 1. Atomic radii increase from top to bottom of the periodic table as \(n\) increases. \(\ce{Cs}\) is located below \(\ce{Na}\) in the same column. Thus, \(\ce{Cs}\) has a larger radius than \(\ce{Na}\).
(c) \(\ce{Sc}\) (\(Z=21\)) and \(\ce{Ni}\) (\(Z=28\)) are located in the same row of the \(d\) block. Across \(d\) block and \(f\) block, atomic radii change is not significant. Therefore, \(\ce{Sc}\) and \(\ce{Ni}\) approximately have the same radius.

Exercises

1. Which of the following set of elements possess similar chemical properties?

1. \(\ce{_{19}K}\) and \(\ce{_{29}Cu}\)
2. \(\ce{_{13}Al}\) and \(\ce{_{14}Si}\)
3. \(_{17}\ce{Cl}\) and \(\ce{_{53}I}\)
4. \(\ce{_{11}Na}\) and \(\ce{_{12}Mg}\)

2. Which of the following statements is true regarding the periodic table?

1. The horizontal rows in the periodic table are known as groups
2. The verticle columns in the periodic table are known as periods
3. In the periodic table, when the atomic number increases, the properties of the elements repeat regularly
4. The periodic table is classified into blocks based on the electron filling pattern into shells

3. Which of the following sets of elements are metals?

1. \(\ce{_{1}H}\) and \(\ce{_{3}Li}\)
2. \(\ce{_{26}Fe}\) and \(\ce{_{29}Cu}\)
3. \(\ce{_{8}O}\) and \(\ce{_{16}S}\)
4. \(\ce{_{5}B}\) and \(\ce{_{14}Si}\)

4. Which of the following sets of elements are nonmetals?

1. \(\ce{_{2}He}\) and \(\ce{_{17}Cl}\)
2. \(\ce{_{1}H}\) and \(\ce{_{20}Ca}\)
3. \(\ce{_{14}Si}\) and \(\ce{_{33}As}\)
4. \(\ce{_{11}Na}\) and \(\ce{_{12}Mg}\)

5. Which of the following elements is a metalloid?

1. \(\ce{_{7}N}\)
2. \(\ce{_{14}Si}\)
3. \(\ce{_{27}Co}\)
4. \(\ce{_{53}I}\)

6. Which of the following properties are unique to metals?

1. Little or no metallic lustre (dull appearance)
2. Poor conductors of electricity and heat
3. Solids under room temperature
4. Low melting points

7. The element highlighted in red in the given periodic table is a

1. Alkali metal
2. Alkaline earth metal
3. Halogen
4. Noble gas

8. Element 4 in the given periodic table is a?

1. Alkali metal
2. Alkaline earth metal
3. Halogen
4. Noble gas

9. Which of the highlighted elements in the given periodic table is an alkali metal as well as an \(s\) block element?

1. Element 1
2. Element 3
3. Element 4
4. Element 2

10. Which of the following statements is true regarding the highlighted elements in the given periodic table?

1. Element 2 is a halogen as well as a \(p\) block element
2. Element 1 is a noble gas
3. Element 4 is a halogen as well as a \(p\) block element
4. Elements 1 and 3 belongs to the \(d\) block

11. Which of the following statements classify the given electron configurations correctly?

1. \(1s^{2}\,2s^{2}2p^{6}\) - \(d\) block element
2. \(1s^{2}\,2s^{2}2p^{6}\,3s^{2}\)- \(p\) block element
3. \(1s^{2}\,2s^{2}2p^{6}\,3s^{2}3p^{6}3d^{2}\,4s^{2}\)- \(f\) block element
4. \(1s^{2}\,2s^{1}\)- \(s\) block element

12. Which of the following statements is incorrect?

1. Representative elements are found in \(s\) area and the first five columns of \(p\) area
2. Transition elements are found in \(d\) area, and they are all metals
3. Inner transition elements are found in \(f\) area, and they are all nonmetals
4. Noble gases are found in the last column of the \(p\) area, and they are all nonmetals

13. How many valence electrons does \(\ce{_{11}Na}\) have?

1. \(1\)
2. \(11\)
3. \(9\)
4. \(3\)

14. How many valence electrons does Group \(13\) have?

1. \(13\)
2. \(3\)
3. \(5\)
4. \(10\)

15. How many valence electrons does \(\ce{_{27}Co}\) have?

1. \(1\)
2. \(6\)
3. \(9\)
4. \(10\)

16. Which of the following atoms has the largest atomic radius?

1. \(\ce{C}\)
2. \(\ce{F}\)
3. \(\ce{Be}\)
4. \(\ce{Mg}\)

17. Which of the following pairS of atoms has nearly the same size?

1. \(\ce{Li}\) and \(\ce{K}\)
2. \(\ce{Al}\) and \(\ce{Cl}\)
3. \(\ce{Ne}\) and \(\ce{Kr}\)
4. \(\ce{Cr}\) and \(\ce{Co}\)

18. Arrange the following atoms in order of increasing first ionisation energy.
    \(\ce{S}\), \(\ce{Ar}\), \(\ce{$\ce{Mg}$ }\), \(\ce{Sr}\) and \(\ce{Ba}\)

1. \(\ce{Ba}\) \(<\) \(\ce{Sr}\) \(<\) \(\ce{Mg}\) \(<\) \(\ce{S}\) \(<\) \(\ce{Ar}\)
2. \(\ce{Ba}\) \(<\) \(\ce{Mg}\) \(<\) \(\ce{S}\) \(<\) \(\ce{Sr}\) \(<\) \(\ce{Ar}\)
3. \(\ce{Ar}\) \(<\) \(\ce{Sr}\) \(<\) \(\ce{Mg}\) \(<\) \(\ce{S}\) \(<\) \(\ce{Ba}\)
4. \(\ce{Ba}\) \(<\) \(\ce{Mg}\) \(<\) \(\ce{Sr}\) \(<\) \(\ce{S}\) \(<\) \(\ce{Ar}\)

19. Which of the following elements has the lowest first ionisation energy?

1. \(\ce{Rb}\)
2. \(\ce{Mo}\)
3. \(\ce{Ag}\)
4. \(\ce{Cs}\)

20. Which of the following statements is true?

1. First ionisation energy increases with increasing atomic radii
2. First ionisation energy increases with decreasing atomic radii
3. First ionisation energy of two \(d\) block elements located in the same period changes significantly
4. First ionisation energy increases down a group

21. Which of the following statements is incorrect regarding the electron affinity?

1. Electron affinity is the energy change when an electron is added to a free atom in the gaseous phase
2. Electron affinity becomes more negative when moving across a period
3. Electron affinity increases down a group
4. There is no clear trend in electron affinity as \(n\) increases

22. Predict which of the following atoms has the most negative electron affinity.

1. \(\ce{K}\)
2. \(\ce{Ti}\)
3. \(\ce{As}\)
4. \(\ce{Br}\)

23. Which of the following elements has the highest electronegativity?

1. \(\ce{P}\)
2. \(\ce{F}\)
3. \(\ce{Cl}\)
4. \(\ce{Br}\)

24. As you move from top to bottom in a group of the periodic table

1. Atomic radii decreases
2. First ionisation energy increases
3. Electronegativity decreases
4. Electron affinity increases

25. Arrange the following atoms in order of increasing electronegativity.
    \(\ce{N}\), \(\ce{O}\), \(\ce{S}\), \(\ce{Se}\)

1. \(\ce{Se}\) \(<\) \(\ce{S}\) \(<\) \(\ce{N}\) \(<\) \(\ce{O}\)
2. \(\ce{Se}\) \(<\) \(\ce{N}\) \(<\) \(\ce{S}\) \(<\) \(\ce{O}\)
3. \(\ce{Se}\) \(<\) \(\ce{S}\) \(<\) \(\ce{O}\) \(<\) \(\ce{N}\)
4. \(\ce{O}\) \(<\) \(\ce{S}\) \(<\) \(\ce{N}\) \(<\) \(\ce{Se}\)