Periodic Table Basics worksheet for learning about elements and their properties.

Let's go through each question on the "Periodic Table Basics" worksheet and provide clear, accurate answers with explanations.

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1) Which elements in the periodic table have one valence electron?

Answer:
Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr)

Explanation:
Elements with one valence electron are found in Group 1 of the periodic table (also called the alkali metals, except hydrogen). These elements have their outermost electron in the s-orbital (ns¹ configuration). Hydrogen is an exception because it’s not a metal but has one valence electron.

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2) What do you notice about the number of valence electrons as you move from left to right across a row in the periodic table?

Answer:
The number of valence electrons increases by one as you move from left to right across a period.

Explanation:
Each group in the periodic table corresponds to a specific number of valence electrons. For example:
- Group 1: 1 valence electron
- Group 2: 2 valence electrons
- ...
- Group 18: 8 valence electrons (except helium, which has 2)

So, moving left to right across a period, the number of valence electrons increases sequentially.

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3) What do you notice about the number of energy levels or shells as you move down a group or column in the periodic table?

Answer:
The number of energy levels (shells) increases as you move down a group.

Explanation:
As you go down a group, each successive element has an additional electron shell (principal energy level). For example:
- Lithium (Li) is in Period 2 → 2 energy levels
- Sodium (Na) is in Period 3 → 3 energy levels
- Potassium (K) is in Period 4 → 4 energy levels

So, atomic size increases down a group due to more shells.

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4) Chemical ________ have similar properties.

Answer:
Chemical elements in the same group have similar properties.

Explanation:
Elements in the same group (vertical column) have the same number of valence electrons, leading to similar chemical behavior. For example, all alkali metals (Group 1) are highly reactive metals that form +1 ions.

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5) Noble gases are also called ________ gases because they don’t react with other elements.

Answer:
Noble gases are also called inert gases because they don’t react with other elements.

Explanation:
Noble gases (Group 18) have a full outer shell of electrons (stable octet), making them very unreactive under normal conditions. This lack of reactivity is why they're called inert gases.

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6) In which family would each of these elements be classified?

- Radium – Alkaline earth metals
- Tin – Metalloids / Post-transition metals (often classified under "metals", but technically a post-transition metal; sometimes referred to as a metalloid due to intermediate properties)
- Iodine – Halogens
- Cesium – Alkali metals

Explanation:
- Radium (Ra) is in Group 2 → Alkaline earth metals
- Tin (Sn) is in Group 14 → typically considered a post-transition metal, though it can exhibit some metalloid characteristics
- Iodine (I) is in Group 17 → Halogens
- Cesium (Cs) is in Group 1 → Alkali metals

> Note: Tin is often grouped with metals, but it has properties between metals and nonmetals.

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7) Write down the number of valence electrons for each of these elements.

- Barium (Ba) = 2
- Lead (Pb) = 4
- Bismuth (Bi) = 5
- Potassium (K) = 1

Explanation:
- Barium (Ba) is in Group 2 → 2 valence electrons
- Lead (Pb) is in Group 14 → 4 valence electrons
- Bismuth (Bi) is in Group 15 → 5 valence electrons
- Potassium (K) is in Group 1 → 1 valence electron

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8) What do you notice about the melting points as you move from left to right across a period in the periodic table?

Answer:
Melting points generally increase from left to right across a period, then decrease toward the noble gases.

Explanation:
From left to right:
- Metals (left side) have metallic bonding; strength increases up to the transition metals.
- The strongest bonds are found in nonmetals like carbon (diamond) and nitrogen/phosphorus compounds.
- However, noble gases have very weak London dispersion forces, so their melting points drop sharply at the end of the period.

So, overall trend: Melting point increases to a peak around the middle (transition metals), then decreases toward the end.

> Example: In Period 3 — Na (low mp), Mg (higher), Al (even higher), Si (very high), P, S, Cl (lower), Ar (lowest).

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✔ Final Answer Summary:

1. Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium, Francium
2. Valence electrons increase by one per group
3. Number of energy levels increases
4. Elements in the same group
5. Inert
6. Radium – Alkaline earth metals; Tin – Post-transition metal (or metalloid); Iodine – Halogens; Cesium – Alkali metals
7. Barium = 2, Lead = 4, Bismuth = 5, Potassium = 1
8. Melting points generally increase then decrease across a period

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