name: ______ instruction: answer the following. please refer to your periodic tabl 1. a. which atom is smaller si or cl? circle your answer. b. what period does the 2 elements belong? 2.) a. which atom is larger? ca or ra? circle your answer. b. which group does the 2 elements belong? 3.) a. which atom is smaller? k or bi? circle your answer. b. what period does the 2 elements belong? 4.) a. which atom is smaller? be or ra? b. what group does the 2 elements belong? 5.) a. which atom is larger? n or br? b. what period does oxygen belong? c. what group does chlorine belong?

Question

Accepted Answer

### 1. a.
# Explanation:
## Step1: Recall atomic size trend
Atomic size decreases across a period (left to right) due to increasing effective nuclear charge. Si (silicon) and Cl (chlorine) are in the same period (period 3). Cl is to the right of Si.
## Step2: Determine smaller atom
Since Cl is further right in period 3, it has a smaller atomic radius than Si.
# Answer: Cl

### 1. b.
# Explanation:
## Step1: Locate Si and Cl on periodic table
Si (atomic number 14) and Cl (atomic number 17) are both in period 3 (row 3) of the periodic table.
# Answer: Period 3

### 2. a.
# Explanation:
## Step1: Recall atomic size trend down a group
Atomic size increases down a group (top to bottom) as new electron shells are added. Ca (calcium) is in group 2, period 4; Ra (radium) is in group 2, period 7. Ra is below Ca.
## Step2: Determine larger atom
Since Ra is lower in group 2, it has a larger atomic radius than Ca.
# Answer: Ra

### 2. b.
# Explanation:
## Step1: Identify group of Ca and Ra
Ca (calcium) and Ra (radium) are both alkaline earth metals, belonging to group 2 (or group IIA) of the periodic table.
# Answer: Group 2 (or Group IIA)

### 3. a.
# Explanation:
## Step1: Analyze positions of K and Bi
K (potassium) is in period 4, group 1; Bi (bismuth) is in period 6, group 15. Atomic size generally increases down a group and decreases across a period, but Bi has more protons and is in a lower period but also further right. However, K is in period 4, Bi in period 6. But across period 4, K is leftmost; Bi is in period 6, but when comparing K (period 4) and Bi (period 6), we also consider the number of electron shells. K has 4 shells, Bi has 6 shells, but Bi is further right. Wait, actually, the atomic radius of K is larger than Bi? Wait no, wait: K is in period 4, group 1 (atomic radius ~243 pm); Bi is in period 6, group 15 (atomic radius ~148 pm). Wait, no, that can't be. Wait, no, I made a mistake. Wait, K is in period 4, Bi is in period 6. But as we move down a group, size increases, but across a period, size decreases. K is in group 1, period 4; Bi is in group 15, period 6. Let's check actual values: K atomic radius (van der Waals) ~275 pm, Bi ~268 pm? Wait, maybe my initial thought was wrong. Wait, no, the correct trend: when comparing K (period 4, group 1) and Bi (period 6, group 15), K has 4 electron shells, Bi has 6. But the effective nuclear charge on Bi is higher (more protons) and it's further right. Wait, actually, Bi is smaller than K? Wait, no, K is a metal, Bi is a metalloid. Wait, let's use the periodic table trends: atomic radius decreases across a period, increases down a group. So K is in period 4, group 1; Bi is in period 6, group 15. So from K to Bi, we move down 2 periods and right 14 groups. The increase in shells (down 2 periods) would tend to increase size, but the increase in protons (right 14 groups) would tend to decrease size. Which effect is stronger? Let's check actual atomic radii: K (atomic radius, metallic) ~227 pm, Bi (atomic radius, metallic) ~167 pm. So Bi is smaller. Wait, so the answer is Bi? Wait, no, wait the question is which is smaller: K or Bi? So Bi is smaller. Wait, I think I messed up earlier. Let's re-express: K is in period 4, group 1. Bi is in period 6, group 15. So moving from K (period 4, group 1) to Bi (period 6, group 15): we go down 2 periods (so add 2 shells) and right 14 groups (so add 14 protons). The increase in protons (nuclear charge) pulls the electrons in more, even with the extra shells. So Bi has a smaller atomic radius than K.
## Step2: Determine smaller atom
Bi is smaller than K.
# Answer: Bi

### 3. b.
# Explanation:
## Step1: Locate K and Bi on periodic table
K (atomic number 19) is in period 4; Bi (atomic number 83) is in period 6. Wait, no, wait Bi is in period 6? Wait, no, Bi is in period 6? Wait, atomic number 83: electron configuration is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³. So period 6. K is [Ar] 4s¹, period 4. Wait, but the question says "the 2 elements" – K and Bi. Wait, K is period 4, Bi is period 6? But that can't be, because the question says "what period does the 2 elements belong?" – maybe a typo, or maybe I made a mistake. Wait, no, K is period 4, Bi is period 6. But that would mean different periods. Wait, maybe the question is miswritten, or I misread. Wait, K is potassium (19), Bi is bismuth (83). So K is period 4, Bi is period 6. But the question says "the 2 elements" – maybe it's a mistake, but perhaps the intended elements are in the same period? Wait, no, K is period 4, Bi is period 6. Wait, maybe I made a mistake in Bi's period. Wait, electron shells: period number is the highest principal quantum number. For Bi: n=6 (6s² 6p³), so period 6. K: n=4 (4s¹), period 4. So they are in different periods. But the question says "what period does the 2 elements belong?" – maybe it's a mistake, but perhaps the user intended K and another element? Wait, no, the question is as given. Wait, maybe I made a mistake in the atomic radius comparison. Wait, K is in period 4, group 1; Bi is in period 6, group 15. So the answer for the period: K is period 4, Bi is period 6. But the question says "the 2 elements" – maybe it's a typo, and the intended elements are in the same period? Wait, no, the question is as given. Alternatively, maybe I misread the elements: K and Bi. So K is period 4, Bi is period 6. But the question asks "what period does the 2 elements belong?" – maybe it's a mistake, but perhaps the answer is that they are in different periods? But that seems odd. Wait, maybe the question is "what periods do the 2 elements belong?" – but the original question is "what period does the 2 elements belong?" – maybe a translation error. Alternatively, maybe I made a mistake in Bi's period. Wait, no, Bi is in period 6. K is in period 4. So perhaps the question has an error, but based on the given elements, K is period 4, Bi is period 6. But that can't be. Wait, maybe the elements are K and Br? No, the question is K or Bi. Wait, maybe the user made a typo. But assuming the question is correct, K is period 4, Bi is period 6. But the question says "the 2 elements" – maybe it's a mistake, but perhaps the intended answer is period 4 for K and period 6 for Bi, but the question is phrased incorrectly. Alternatively, maybe I misread the element: Bi is bismuth, atomic number 83, period 6. K is potassium, atomic number 19, period 4. So the answer is that K is in period 4 and Bi is in period 6. But the question says "what period does the 2 elements belong?" – maybe it's a mistake, but perhaps the intended elements are in the same period, and there's a typo. Alternatively, maybe I made a mistake in the atomic radius comparison. Wait, going back to the atomic radius: K has a larger atomic radius than Bi, so Bi is smaller. And their periods: K is period 4, Bi is period 6. But the question asks "what period does the 2 elements belong?" – maybe it's a mistake, but perhaps the answer is that they are in different periods, but that's unlikely. Wait, maybe the question is "what periods do the 2 elements belong?" – but the original is "what period does the 2 elements belong?" – maybe a grammar error. Alternatively, maybe the elements are K and Sb? No, the question is K or Bi. I think there's a mistake in the question, but based on the given elements, K is period 4, Bi is period 6. But since the question asks "what period does the 2 elements belong?" – maybe it's a typo, and the intended elements are in the same period. Alternatively, maybe I made a mistake. Wait, let's check the periodic table again: K (19) is period 4, group 1. Bi (83) is period 6, group 15. So they are in different periods. So the answer is that K is in period 4 and Bi is in period 6. But the question is phrased as "what period does the 2 elements belong?" – maybe it's a mistake, but I'll answer based on the elements: K is period 4, Bi is period 6. But perhaps the question intended K and another element in period 4, like K and Br, but no, the question is K or Bi. So I think there's an error, but I'll proceed.
# Answer: K is in Period 4, Bi is in Period 6 (Note: Possible question error as they are in different periods)

### 4. a.
# Explanation:
## Step1: Recall atomic size trends
Atomic size increases down a group (top to bottom) as new electron shells are added. Be (beryllium) is in group 2, period 2; Ra (radium) is in group 2, period 7. Ra is below Be.
## Step2: Determine smaller atom
Since Be is higher in group 2, it has a smaller atomic radius than Ra.
# Answer: Be

### 4. b.
# Explanation:
## Step1: Identify group of Be and Ra
Be (beryllium) and Ra (radium) are both alkaline earth metals, belonging to group 2 (or group IIA) of the periodic table.
# Answer: Group 2 (or Group IIA)

### 5. a.
# Explanation:
## Step1: Analyze positions of N and Br
N (nitrogen) is in period 2, group 15; Br (bromine) is in period 4, group 17. Atomic size generally increases down a group and decreases across a period. Br is in a lower period (more electron shells) and further right, but the increase in shells (down 2 periods) has a stronger effect on size than the increase in protons (right 2 groups).
## Step2: Determine larger atom
Br has more electron shells (4 vs. 2 for N) and thus a larger atomic radius.
# Answer: Br

### 5. b.
# Explanation:
## Step1: Locate Oxygen on periodic table
Oxygen (O) has an atomic number of 8. Its electron configuration is 1s² 2s² 2p⁴, so the highest principal quantum number (n) is 2, meaning it is in period 2.
# Answer: Period 2

### 5. c.
# Explanation:
## Step1: Locate Chlorine on periodic table
Chlorine (Cl) has an atomic number of 17. It is a halogen, belonging to group 17 (or group VIIA) of the periodic table (group number is 17, or sometimes referred to as group 7A in older numbering, but modern numbering is 1 to 18, so group 17).
# Answer: Group 17 (or Group VIIA)

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QUESTION IMAGE

Question

Explanation:

1. a.

Step1: Recall atomic size trend

Step2: Determine smaller atom

Step1: Locate Si and Cl on periodic table

Step1: Recall atomic size trend down a group

Step2: Determine larger atom

Answer:

1. b.