Unit 1: Periodicity

Question 1

Periodic Law

Answer 1

the properties of elements recur in a repeating patter when arranged according to increasing atomic number.

Answer 2

• Dmitri Mendeleev (1834-1907) - 65 elements
• Aligned his version of periodic table by mass
• At time alignment left gaps
• Predicted eka-silicon
• Discovered by Clemens Winkler as germanium,
• Now atomic number not mass

Question 3

Breakdown of Periodic Table

Answer 3

• Metallic character
• Representative elements (electron configuration)
• s & p; (d & f block transition)

Question 4

Metallic character

Answer 4

tendency of an element to be metallic in nature;

lose electrons

Question 5

Nonmetallic character

Answer 5

tendency of an element to not be metallic in nature; generally gain electrons

Question 6

Metallic Character

Metal

Answer 6

tends to be a solid, bright luster, high density, high melting point, good conductor

Question 7

Metallic Character

Nonmetal

Answer 7

an element that usually has low density, low melting point, and is a poor conductor of heat and electricity.

Question 8

Metallic Character

Metalloid

Answer 8

an element that typically has properties midway between those of a metal and nonmetal.

Question 9

Question 10

Table by Group

What is a group?

What is a Period?

Answer 10

• Representative Elements (main group)
• Transition elements (d-block/ f-block)
• Group/Family – a vertical column in the periodic table.
• Period – a horizontal row in the periodic table
• In same group, similar properties; repeat along period

Question 11

Element Groups

Answer 11

Group IA (1) elements, alkali metals – tend to be highly reactive, make 1+ cations

Group IIA (2), alkaline earth metals – less reactive than group IA; make 2+ cations

Group VIIA (17), the halogens – very reactive nonmetals – make 1- anions

Group VIIA (18), the noble gases – nonreactive, gases

Question 12

Ions

Cations vs Anions

Answer 12

• Cations – lose electrons, positive
• Anions – gain electrons, negative
• Metals tend toward cation,
• nonmetals toward anion
• Predict ionic charge:
• Valence state – electrons

Question 13

Octet rule

Answer 13

atoms adopt the valence configuration of the nearest noble gas

Representative elements:

• Group number corresponds to # valence electrons
• gain/lose to achieve octet

Period 3:

Ne – 8; Na – 1; Mg – 2; Al – 3; Si – 4; P – 5; S – 6; Cl – 7; Ar – 8

Na+; Mg2+; Al3+; Si4+/Si4-; P3-; S2-; Cl-

Question 14

Predict the charge on the following atoms as ions:

• Ca
• Te
• Ba
• B
• Br