Introduction to Periodic Table worksheet with questions on element properties, classification, and electron configurations.

Let’s go step by step through each part of the worksheet.

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Part 1: Fill in the correct name.

We’re being asked to match historical scientists or contributors to their achievements related to the periodic table.

a) “Predicted the properties for elements missing from his periodic table”
→ This is Dmitri Mendeleev. He left gaps in his table and predicted what those missing elements would be like.

b) “Discovered that each element has a unique atomic number”
→ This is Henry Moseley. He used X-rays to show that atomic number (not mass) was the key to ordering elements.

c) “Arranged elements according to the atomic number”
→ Again, this is Henry Moseley, but sometimes also credited to later chemists who adopted his idea. However, since Moseley discovered it, he’s the best fit here. But wait — actually, after Moseley’s discovery, modern periodic tables are arranged by atomic number. So if we need a person, it’s still Moseley. But let’s check context — sometimes textbooks say “the modern periodic table arranges by atomic number,” so maybe they want “Modern Periodic Table” or “Scientists after Moseley.” But looking at common answers, Mendeleev arranged by mass, Moseley by atomic number. So c = Moseley

Wait — let me double-check:

Actually, Mendeleev arranged by *atomic mass*, and noticed patterns. Moseley proved atomic *number* was the real organizer. So:

d) “Arranged elements according to the atomic mass” → Mendeleev

e) “Had some elements out of place” → Because Mendeleev went by mass, some elements didn’t fit perfectly (like tellurium and iodine). So again, Mendeleev

f) “Place all elements in the right place according to properties” → This sounds like the goal of the modern table, which uses atomic number. So probably Moseley or just “Modern Scientists”. But since Moseley made the key discovery, and others built on it, perhaps the answer expected is Moseley for c and f? Hmm.

Wait — let’s think differently. Maybe:

- a) Mendeleev (predicted missing elements)
- b) Moseley (discovered atomic number uniqueness)
- c) Moseley (arranged by atomic number — though technically he didn’t make the full table, he provided the method)
- d) Mendeleev (arranged by atomic mass)
- e) Mendeleev (had elements out of place because of mass ordering)
- f) Modern periodic table / Scientists using atomic number — but since we need names, perhaps Moseley again? Or maybe “No single person” — but that’s not helpful.

Actually, in many school worksheets, they accept:

a) Mendeleev
b) Moseley
c) Moseley
d) Mendeleev
e) Mendeleev
f) Moseley (or sometimes “Modern Chemists”) — but to keep consistent, let’s use Moseley for c and f.

But wait — another thought: sometimes “f” refers to how today’s table places everything correctly based on properties AND atomic number — so maybe it’s not one person. But since the question says “fill in the correct name”, and only two names are involved, likely:

Final decision for Part 1:

a) Dmitri Mendeleev
b) Henry Moseley
c) Henry Moseley
d) Dmitri Mendeleev
e) Dmitri Mendeleev
f) Henry Moseley (since he enabled correct placement via atomic number)

But let’s verify with standard knowledge:

Yes — Mendeleev: arranged by mass, predicted missing elements, had some misplaced.
Moseley: showed atomic number is fundamental, allowing correct arrangement.

So f might be better as “Scientists using Moseley’s work” — but since we must pick a name, and Moseley is the key figure, we’ll go with him.

Alternatively, maybe f is meant to be “The Modern Periodic Table” — but again, the instruction says “name”, implying person.

I think safest is:

a) Mendeleev
b) Moseley
c) Moseley
d) Mendeleev
e) Mendeleev
f) Moseley

Okay, moving on.

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Part 2: Identify as metal, nonmetal, metalloid.

Recall:

- Metals: shiny, conductive, malleable, usually solid (except Hg), lose electrons easily. Left side and middle of table.
- Nonmetals: poor conductors, brittle, gain electrons. Right side.
- Metalloids: have properties of both; along the zigzag line (B, Si, Ge, As, Sb, Te, Po).

Now:

a) Sodium → Group 1, alkali metal → Metal

b) Chlorine → Group 17, halogen → Nonmetal

c) Silicon → Along zigzag, classic metalloid → Metalloid

d) Iron → Transition metal → Metal

e) Carbon → Right side, forms covalent bonds → Nonmetal

f) Germanium → Below silicon, also metalloid → Metalloid

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Part 3: Noble gas configuration

Noble gas configuration means writing the electron configuration using the previous noble gas in brackets, then adding the remaining electrons.

First, recall noble gases: He (2), Ne (10), Ar (18), Kr (36), Xe (54), Rn (86)

Now:

a) Lithium (Li) — atomic number 3
Full config: 1s² 2s¹
Previous noble gas: Helium (He) = 1s²
So: [He] 2s¹

b) Magnesium (Mg) — atomic number 12
Full: 1s² 2s² 2p⁶ 3s² → or [Ne] 3s² (since Ne is 10)

c) Copper (Cu) — atomic number 29
Exception! Expected: [Ar] 4s² 3d⁹
Actual: [Ar] 4s¹ 3d¹⁰ (more stable)
So: [Ar] 4s¹ 3d¹⁰

d) Bromine (Br) — atomic number 35
Previous noble gas: Argon (18)
Then: 4s² 3d¹⁰ 4p⁵ → so [Ar] 4s² 3d¹⁰ 4p⁵

e) Silver (Ag) — atomic number 47
Exception! Expected: [Kr] 5s² 4d⁹
Actual: [Kr] 5s¹ 4d¹⁰
So: [Kr] 5s¹ 4d¹⁰

f) Tellurium (Te) — atomic number 52
Previous noble gas: Krypton (36)
Then: 5s² 4d¹⁰ 5p⁴ → so [Kr] 5s² 4d¹⁰ 5p⁴

Wait — order matters? Usually we write in order of shell: so 5s, then 4d, then 5p — yes, that’s fine.

Double-check:

- Li: [He] 2s¹ ✔️
- Mg: [Ne] 3s² ✔️
- Cu: [Ar] 4s¹ 3d¹⁰ ✔️ (exception)
- Br: [Ar] 4s² 3d¹⁰ 4p⁵ ✔️
- Ag: [Kr] 5s¹ 4d¹⁰ ✔️ (exception)
- Te: [Kr] 5s² 4d¹⁰ 5p⁴ ✔️

All good.

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Final Answer:

Part 1:
a) Dmitri Mendeleev
b) Henry Moseley
c) Henry Moseley
d) Dmitri Mendeleev
e) Dmitri Mendeleev
f) Henry Moseley

Part 2:
a) Metal
b) Nonmetal
c) Metalloid
d) Metal
e) Nonmetal
f) Metalloid

Part 3:
a) [He] 2s¹
b) [Ne] 3s²
c) [Ar] 4s¹ 3d¹⁰
d) [Ar] 4s² 3d¹⁰ 4p⁵
e) [Kr] 5s¹ 4d¹⁰
f) [Kr] 5s² 4d¹⁰ 5p⁴