Question

type the element’s name that fits each description.
part 1 of 4
a main group element in period 2, group 1a.
part 2 of 4
a halogen in period 4.

Explanation:

Part 1 of 4

Step 1: Recall Periodic Table Structure

Periods are horizontal rows, groups (columns) 1A are alkali metals. Period 2, group 1A: look at row 2 (period 2) and column 1A.

Step 2: Identify Element

Period 2 (second row) elements: Li, Be, B, C, N, O, F, Ne. Group 1A (first column) in period 2 is Lithium? Wait, no: period 1: H, He; period 2: Li (group 1A), Be (2A), etc. Wait, group 1A is alkali metals. Period 2, group 1A: Lithium? No, wait, period 2: Li is in period 2, group 1A? Wait, no: period 1: H, He; period 2: Li (atomic number 3), Na is period 3. Wait, yes: period 2 (n=2) has Li (Z=3) in group 1A. Wait, no, Li is in period 2? Wait, electron configuration: Li is 1s²2s¹, so n=2, so period 2. Group 1A (alkali metals) in period 2 is Lithium? Wait, no, wait: group 1A is first column. Period 2: Li (group 1A), Be (2A), B (13), C (14), N (15), O (16), F (17), Ne (18). So group 1A, period 2: Lithium? Wait, no, Li is in period 2? Wait, yes, Li has principal quantum number n=2 for valence shell, so period 2. So the element is Lithium? Wait, no, wait: period 2, group 1A: Lithium (Li). Wait, but wait, Na is period 3. So yes, period 2, group 1A is Lithium? Wait, no, I think I made a mistake. Wait, period 1: H, He (n=1); period 2: Li (n=2), Be (n=2), etc. So group 1A (column 1) in period 2 is Li (atomic number 3). So the element is Lithium? Wait, no, wait: group 1A is alkali metals, period 2: Li, period 3: Na, period 4: K, etc. So yes, period 2, group 1A is Lithium? Wait, no, Li is in period 2? Wait, electron configuration: Li: 1s² 2s¹, so n=2, so period 2. So the element is Lithium? Wait, no, wait, maybe I confused. Wait, the main group element in period 2, group 1A: Lithium (Li).

Part 2 of 4

Step 1: Recall Halogens and Periods

Halogens are group 17 (7A). Period 4: elements in period 4 (n=4) and group 17.

Step 2: Identify Halogen in Period 4

Halogens: F (period 2), Cl (period 3), Br (period 4), I (period 5), At (period 6). So period 4, group 17: Bromine (Br). Because period 4: n=4, Br has electron configuration [Ar] 4s²3d¹⁰4p⁵, so n=4 (period 4), group 17 (halogens). So the halogen in period 4 is Bromine.

Answer:

s:
Part 1: Lithium (Wait, no, wait: period 2, group 1A: Lithium? Wait, no, Li is in period 2? Wait, yes, Li is in period 2. Wait, but I think I messed up. Wait, period 2: Li (Z=3), Na (Z=11) is period 3. So group 1A, period 2: Li. So part 1 answer: Lithium.

Part 2: Bromine (Br) is the halogen in period 4 (group 17, period 4).

(Note: For part 1, correction: Wait, group 1A, period 2: Lithium (Li). For part 2, halogen in period 4: Bromine (Br).)

Part 1 of 4 Answer: Lithium

Part 2 of 4 Answer: Bromine