module 5
periodicity
you should be able to
- use the periodic table to locate elements, identify groups and their properties
- describe the trends in the periodic table – atomic radius, electronegativity, ionization energy, electron affinity, and ionic radius
1. for each of the following, use the periodic table to determine the number of valence electrons in an atom of the element.
___ ne ___ s ___ mg ___ sn ___ c ___ al
___ te ___ cs ___ bi ___ br ___ ga ___ p
2. for each of the following, use the periodic table to determine the number of occupied energy levels in an atom of the element.
___ ne ___ s ___ mg ___ sn ___ c ___ al
___ te ___ cs ___ bi ___ br ___ ga ___ p
3. for each of the following, use the periodic table to determine if the element is a metal (m), nonmetal (nm), or metalloid (me).
___ w ___ s ___ mg ___ b ___ ca ___ ar
___ h ___ cs ___ zn ___ br ___ sb ___ u
4. atomic radius
___ the distance between ___ of two like ___.
___ across a period (due to increased attraction of more positive nuclei to electron clouds)
___ down a family (due to addition of an energy level)
5. electron affinity
amount of ___ when an ___ gains an ___
___ across a period
___ down a family
6. ionization energy
amount of ___ required to ___ an ___ from a neutral ___
___ across a period
___ down a family
for each of the sets of elements, identify the element that has the characteristic
7. n p as smallest ionization energy
8. k ca sc largest atomic mass
9. al si p greatest electron affinity
10. ga al si largest atomic radius

Question

module 5
periodicity
you should be able to
 - use the periodic table to locate elements, identify groups and their properties
 - describe the trends in the periodic table – atomic radius, electronegativity, ionization energy, electron affinity, and ionic radius
1. for each of the following, use the periodic table to determine the number of valence electrons in an atom of the element.
___ ne ___ s ___ mg ___ sn ___ c ___ al
___ te ___ cs ___ bi ___ br ___ ga ___ p
2. for each of the following, use the periodic table to determine the number of occupied energy levels in an atom of the element.
___ ne ___ s ___ mg ___ sn ___ c ___ al
___ te ___ cs ___ bi ___ br ___ ga ___ p
3. for each of the following, use the periodic table to determine if the element is a metal (m), nonmetal (nm), or metalloid (me).
___ w ___ s ___ mg ___ b ___ ca ___ ar
___ h ___ cs ___ zn ___ br ___ sb ___ u
4. atomic radius
___ the distance between ___ of two like ___.
___ across a period (due to increased attraction of more positive nuclei to electron clouds)
___ down a family (due to addition of an energy level)
5. electron affinity
amount of ___ when an ___ gains an ___
___ across a period
___ down a family
6. ionization energy
amount of ___ required to ___ an ___ from a neutral ___
___ across a period
___ down a family
for each of the sets of elements, identify the element that has the characteristic
7. n  p  as  smallest ionization energy
8. k  ca  sc  largest atomic mass
9. al  si  p  greatest electron affinity
10. ga  al  si  largest atomic radius

Accepted Answer

# Explanation:
## Step1: Find valence electrons (Group #)
Valence electrons = main group number (for main group elements; transition metals: group 3-12, valence e⁻ vary, but Sn (14) has 4, Bi (15) has 5)
- Ne (18): 8; S (16): 6; Mg (2): 2; Sn (14): 4; C (14): 4; Al (13): 3
- Te (16): 6; Cs (1): 1; Bi (15): 5; Br (17): 7; Ga (13): 3; P (15): 5

## Step2: Count occupied energy levels (Period #)
Occupied levels = period number of the element
- Ne (2): 2; S (3): 3; Mg (3): 3; Sn (5): 5; C (2): 2; Al (3): 3
- Te (5): 5; Cs (6): 6; Bi (6): 6; Br (4): 4; Ga (4): 4; P (3): 3

## Step3: Classify metal/nonmetal/metalloid
Use periodic table regions: metals (left/center), nonmetals (right), metalloids (staircase)
- W (M); S (NM); Mg (M); B (ME); Ca (M); Ar (NM)
- H (NM); Cs (M); Zn (M); Br (NM); Sb (ME); U (M)

## Step4: Define/describe atomic radius
Fill in key terms and trends:
- **the distance between the nuclei of two like atoms**
- **Decreases** across a period (due to increased attraction of more positive nuclei to electron clouds)
- **Increases** down a family (due to addition of an energy level)

## Step5: Define/describe electron affinity
Fill in key terms and trends:
- amount of **energy released/absorbed** when an **atom** gains an **electron**
- **Increases (becomes more negative)** across a period
- **Decreases (becomes less negative)** down a family

## Step6: Define/describe ionization energy
Fill in key terms and trends:
- amount of **energy** required to **remove** an **electron** from a neutral **atom**
- **Increases** across a period
- **Decreases** down a family

## Step7: Find smallest ionization energy
Ionization energy decreases down a group: N, P, As (Group 15) → As is lowest
## Step8: Find largest atomic mass
Atomic mass increases across a period: K, Ca, Sc (Period 4) → Sc is largest
## Step9: Find greatest electron affinity
Electron affinity increases across a period (Group 13-15 to 17): Al, Si, P → Si (P has stable half-filled p-subshell, lower affinity)
## Step10: Find largest atomic radius
Atomic radius increases down a group, decreases across period: Ga (4), Al (3), Si (3) → Ga is largest

# Answer:
1. Ne: 8; S: 6; Mg: 2; Sn: 4; C: 4; Al: 3; Te: 6; Cs: 1; Bi: 5; Br: 7; Ga: 3; P: 5
2. Ne: 2; S: 3; Mg: 3; Sn: 5; C: 2; Al: 3; Te: 5; Cs: 6; Bi: 6; Br: 4; Ga: 4; P: 3
3. W: M; S: NM; Mg: M; B: ME; Ca: M; Ar: NM; H: NM; Cs: M; Zn: M; Br: NM; Sb: ME; U: M
4. the distance between **the nuclei** of two like **atoms**; **Decreases** across a period; **Increases** down a family
5. amount of **energy released/absorbed** when an **atom** gains an **electron**; **Increases (more negative)** across a period; **Decreases (less negative)** down a family
6. amount of **energy** required to **remove** an **electron** from a neutral **atom**; **Increases** across a period; **Decreases** down a family
7. As
8. Sc
9. Si
10. Ga

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Question

Explanation:

Step1: Find valence electrons (Group #)

Step2: Count occupied energy levels (Period #)

Step3: Classify metal/nonmetal/metalloid

Step4: Define/describe atomic radius

Step5: Define/describe electron affinity

Step6: Define/describe ionization energy

Step7: Find smallest ionization energy

Step8: Find largest atomic mass

Step9: Find greatest electron affinity

Step10: Find largest atomic radius

Answer: