Ch. 3: “Atoms & the Ch. 3: “Atoms & the Periodic Table”Periodic Table”

Section 2: “A Guided Tour of Section 2: “A Guided Tour of the Periodic Table”the Periodic Table”

1. Explain how you can 1. Explain how you can determine the number of determine the number of neutrons an atom has…neutrons an atom has… Subtract the atomic number (Z) Subtract the atomic number (Z)

from the atomic mass (A).from the atomic mass (A).

2. Calculate how many 2. Calculate how many neutrons a P-32 atom neutrons a P-32 atom has.has. A - Z = 32 - 15 = 17 neutronsA - Z = 32 - 15 = 17 neutrons

3. Name the element…3. Name the element…

a. lithiuma. lithium

b. magnesiumb. magnesium

c. copperc. copper

d. bromined. bromine

e. heliume. helium

f. sulfurf. sulfur

g. sodiumg. sodium

h. ironh. iron

i. potassiumi. potassium

4. Compare the number of 4. Compare the number of valence electrons between O & valence electrons between O & Se. Are O & Se in the same Se. Are O & Se in the same period or group?period or group? Both elements have six valence Both elements have six valence

electrons. They are in the same electrons. They are in the same group/family but not the same group/family but not the same period.period.

5. Describe how a Na atom 5. Describe how a Na atom differs from a Na ion. Which differs from a Na ion. Which form of Na is more likely to be form of Na is more likely to be found in nature?found in nature? A Na atom is uncharged & has one A Na atom is uncharged & has one

valence electron. A Na ion is a Na valence electron. A Na ion is a Na atom that has lost its valence atom that has lost its valence electron to become Naelectron to become Na++. The ion is . The ion is more often found in nature because more often found in nature because the atom easily loses the valence the atom easily loses the valence electron to achieve an outmost electron to achieve an outmost energy level that resembles the energy level that resembles the noble gas Ne.noble gas Ne.

6. Predict which isotope of 6. Predict which isotope of N is more commonly found, N is more commonly found, N-14 or N-15.N-14 or N-15. Atomic mass is a weighted Atomic mass is a weighted

average of all the isotopes. The average of all the isotopes. The average atomic mass for N is average atomic mass for N is 14.01 amu, so N-14 is more 14.01 amu, so N-14 is more commonly found.commonly found.

7. Describe why the elements 7. Describe why the elements in the periodic table are in the periodic table are arranged in order of increasing arranged in order of increasing atomic number.atomic number. When arranged according to When arranged according to

atomic number, the properties of atomic number, the properties of the elements repeat in a regular the elements repeat in a regular pattern.pattern.

8. Critical Thinking8. Critical Thinking

Scientists would predict that Scientists would predict that technetium would have the same technetium would have the same properties as other elements in properties as other elements in the same group, such as the same group, such as manganese or rhenium.manganese or rhenium.