Let's solve each question step by step using the periodic table provided in the image and general knowledge of chemistry.
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1. How many elements are currently recognized in the periodic table?
✔ Answer: 118
Explanation: As of now, there are 118 confirmed elements in the periodic table, with atomic numbers from 1 (hydrogen) to 118 (oganesson). The periodic table shown includes up to element 118.
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2. What is the atomic number of helium (He)?
✔ Answer: 2
Explanation: Helium is located in period 1, group 18. Its atomic number is 2, meaning it has 2 protons in its nucleus.
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3. How many elements are in the first period of the periodic table?
✔ Answer: 2
Explanation: The first period consists of only two elements: hydrogen (H) and helium (He).
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4. What is the symbol and atomic number of the element with 26 protons?
✔ Answer: Fe, 26
Explanation: The atomic number equals the number of protons. Element with atomic number 26 is iron (Fe), which is found in period 4, group 8.
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5. How many valence electrons does carbon (C) have?
✔ Answer: 4
Explanation: Carbon is in group 14 (or 4A), and elements in this group have 4 valence electrons.
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6. Which element has the symbol "Na" and atomic number 11?
✔ Answer: Sodium
Explanation: Na is the chemical symbol for sodium, and its atomic number is 11. It’s in group 1, period 3.
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7. How many groups are there in the periodic table?
✔ Answer: 18
Explanation: The periodic table has 18 vertical columns called groups. These range from Group 1 on the left to Group 18 on the right.
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8. Calculate the average atomic mass of an element with two isotopes: one with a mass of 10 amu and abundance of 80%, and another with a mass of 12 amu and abundance of 20%.
✔ Answer: 10.4 amu
Calculation:
Average atomic mass = (mass₁ × abundance₁) + (mass₂ × abundance₂)
= (10 amu × 0.80) + (12 amu × 0.20)
= 8.0 + 2.4
=
10.4 amu
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9. Which element has the highest electronegativity value?
✔ Answer: Fluorine (F)
Explanation: Electronegativity increases across a period and decreases down a group. Fluorine (F), in group 17, period 2, has the highest electronegativity value (about 3.98 on the Pauling scale).
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10. What is the electron configuration of nitrogen (N)?
✔ Answer: 1s² 2s² 2p³
Explanation: Nitrogen has an atomic number of 7, so it has 7 electrons. Filling orbitals in order:
- 1s² → 2 electrons
- 2s² → 2 more (total 4)
- 2p³ → 3 more (total 7)
So, full configuration:
1s² 2s² 2p³
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✔ Final Answers:
1. 118
2. 2
3. 2
4. Fe, 26
5. 4
6. Sodium
7. 18
8. 10.4 amu
9. Fluorine (F)
10. 1s² 2s² 2p³
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Parent Tip: Review the logic above to help your child master the concept of periodic table trends worksheet answers.
