Chemistry worksheet focusing on the periodic table, featuring questions and a table to identify elements based on specific atomic properties.

Let's solve each question step by step based on the periodic table and basic chemistry principles.

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1. What is the element symbol for Californium?

- Answer: Cf
- Californium is a synthetic element with atomic number 88.
- Its chemical symbol is Cf.

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2. How many protons are present in an atom of Bismuth?

- Answer: 83
- The number of protons in an atom is equal to its atomic number.
- Bismuth (Bi) has an atomic number of 83, so it has 83 protons.

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3. To which group element does Argon belong?

- Answer: Group 18
- Argon (Ar) is a noble gas.
- Noble gases are located in Group 18 of the periodic table.

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4. All families have the same number of ________ electrons.

- Answer: valence
- Elements in the same group (family) have the same number of valence electrons.
- This is why they exhibit similar chemical properties.

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5. Nobel gases have a ________ valence shell.

- Answer: full
- Noble gases have a completely filled valence shell, making them very stable and unreactive.
- (Note: "Nobel" is likely a typo; it should be Noble gases.)

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6. Alkaline-earth metals are the elements in the ____ column.

- Answer: 2
- Alkaline-earth metals are found in Group 2 of the periodic table.
- Examples include Be, Mg, Ca, Sr, Ba, Ra.

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7. Write down the element from the set that matches the given criteria.

We are given a table with four atoms (Chlorine, Sodium, Silicon, Aluminum) and three criteria:

| Criteria | Atom 1 | Atom 2 | Atom 3 | Atom 4 | Element |
|---------------------|------------|------------|------------|------------|---------|
| Largest size | Chlorine | Sodium | Silicon | Aluminum | |
| Highest electronegativity | Calcium | Beryllium | Radium | Magnesium | |
| Ionization energy | Calcium | Bromine | Arsenic | Iron | |

We need to determine which element best fits each criterion.

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#### a) Largest size (atomic radius)

- Atoms listed: Chlorine, Sodium, Silicon, Aluminum
- Trends:
- Atomic size increases down a group.
- Atomic size decreases from left to right across a period.
- These elements are all in Period 3:
- Na (leftmost), then Mg, Al, Si, P, S, Cl (rightmost)
- So, Sodium (Na) has the largest atomic size because it's on the far left.
- Answer: Sodium

> ✔ Element: Sodium

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#### b) Highest electronegativity

- Electronegativity increases from left to right across a period and decreases down a group.
- Atoms listed: Calcium, Beryllium, Radium, Magnesium
- These are all alkaline-earth metals (Group 2):
- Be (top), Mg, Ca, Ra (bottom)
- Electronegativity decreases down the group → Beryllium is the most electronegative among them.
- But wait — let’s check actual values:
- Be: ~1.57
- Mg: ~1.31
- Ca: ~1.00
- Ra: ~0.9
- So yes, Beryllium has the highest electronegativity.

> ✔ Element: Beryllium

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#### c) Ionization energy

- Ionization energy increases from left to right across a period and decreases down a group.
- Atoms listed: Calcium, Bromine, Arsenic, Iron
- Let’s analyze their positions:
- Calcium (Ca): Group 2, Period 4
- Iron (Fe): Group 8, Period 4
- Arsenic (As): Group 15, Period 4
- Bromine (Br): Group 17, Period 4
- All in Period 4, so we compare across the period.
- Ionization energy generally increases across a period (with exceptions).
- Bromine is on the far right (except noble gas), so it has high ionization energy.
- Among these, Bromine has the highest ionization energy.
- Check values:
- Ca: ~590 kJ/mol
- Fe: ~760 kJ/mol
- As: ~947 kJ/mol
- Br: ~1140 kJ/mol
- Yes, Bromine has the highest ionization energy.

> ✔ Element: Bromine

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✔ Final Answers:

1. Cf
2. 83
3. Group 18
4. valence
5. full
6. 2
7.
- Largest size: Sodium
- Highest electronegativity: Beryllium
- Ionization energy: Bromine

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✔ Completed Table:

| Criteria | Atom 1 | Atom 2 | Atom 3 | Atom 4 | Element |
|---------------------|------------|------------|------------|------------|--------------|
| Largest size | Chlorine | Sodium | Silicon | Aluminum | Sodium |
| Highest electronegativity | Calcium | Beryllium | Radium | Magnesium | Beryllium|
| Ionization energy | Calcium | Bromine | Arsenic | Iron | Bromine |

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