Question

1. does element a or element b have a higher electronegativity? a. element a because it is smaller and holds electrons more tightly. b. element b because it is larger and holds electrons more tightly. c. element a because it is a nonmetal and wants to lose electrons. d. element b because it is a metal and wants to gain electrons. 12. which element would have the following lewis dot diagram? a. chlorine b. helium c. lithium d. phosphorous 13. how many valence electrons does an atom of carbon (c) have? a. 1 b. 2 c. 4 d. 6 14. which of these are alkaline earth metals? cu, sr, cd, au, ca, be, co a. sr, be, ca b. cu, cd, au, co c. cu, au, be, co d. all 7 elements 15. which elements would be in period 2? *note these models are not drawn to scale a) a and d only b) c and e only c) b, c and e only d) none of these 16. refer to the elements in #15. which elements have the highest shielding effect? a) a and d only b) c and e only c) b, c and e only 17. what is the oxidation number (charge) of fluorine? a) -7 b) -3 c) -1 d) +7 18. which element would be the smallest? a) oxygen b) sulfur c) selenium 19. which element has the lowest ionization energy? a) ca b) ge c) se d) br 20. which element has the largest electronegativity? a) mg b) sr c) ba d) be

Explanation:

Step1: Recall electronegativity trends

Electronegativity increases across a period and decreases down a group. Smaller atoms hold electrons more tightly and have higher electronegativity.

Step2: Analyze element A and B

Element A is smaller, so it has higher electronegativity.

Step3: Recall Lewis - dot diagram rules

The Lewis - dot diagram shows valence electrons. Chlorine has 7 valence electrons, helium has 2 (a duet), lithium has 1, and phosphorus has 5. The given diagram has 5 dots, so it is phosphorus.

Step4: Recall valence - electron number for carbon

Carbon has an atomic number of 6 and its electron configuration is 1s²2s²2p². It has 4 valence electrons.

Step5: Recall alkaline - earth metals

Alkaline - earth metals are in Group 2 of the periodic table. Sr (strontium), Be (beryllium), and Ca (calcium) are in Group 2.

Step6: Recall periodic - table periods

Elements in period 2 have 2 electron shells. From the diagrams, A and D have 2 electron shells.

Step7: Recall shielding - effect concept

The shielding effect increases with the number of electron shells. Elements B, C, and E have more electron shells compared to A and D, so they have a higher shielding effect.

Step8: Recall oxidation - number of fluorine

Fluorine is the most electronegative element and has an oxidation number of - 1 in most of its compounds.

Step9: Recall atomic - size trends

Atomic size decreases across a period and increases down a group. Oxygen is the smallest among oxygen, sulfur, and selenium as they are in the same group and oxygen is at the top.

Step10: Recall ionization - energy trends

Ionization energy increases across a period and decreases down a group. Ca is in Group 2 and has the lowest ionization energy among Ca, Ge, Se, and Br as it is a metal and in a lower group.

Step11: Recall electronegativity trends

Electronegativity increases across a period and decreases down a group. Be has the largest electronegativity among Mg, Sr, Ba, and Be as they are in the same group and Be is at the top.

Answer:

1. a. Element A because it is smaller and holds electrons more tightly.
2. d. phosphorus
3. c. 4
4. a. Sr, Be, Ca
5. a. A and D only
6. c. B, C and E only
7. c. - 1
8. A) oxygen
9. A) Ca
10. D) Be