Atomic Structure and the Periodic Table Quiz

Grade 9 · Science · Quiz

Test your knowledge of atomic structure, subatomic particles, and how the periodic table is organized.

Questions

Which particle is found in the nucleus and has no charge?
1. Electron
2. Proton
3. Neutron
4. Ion
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Answer: Neutron
Neutrons are neutral particles in the nucleus. Protons are positive and electrons are negative.
Sodium has atomic number 11. How many electrons does a neutral sodium atom have?
1. 11
2. 12
3. 23
4. 22
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Answer: 11
A neutral atom has equal protons and electrons. Sodium's atomic number is 11, so it has 11 electrons.
Isotopes of an element always have different chemical properties.
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Answer: False
Isotopes differ in neutron count and mass but have identical chemical properties because chemistry depends on electrons, not neutrons.
Elements are arranged in the modern periodic table in order of increasing:
1. Mass number
2. Atomic mass
3. Atomic number
4. Number of neutrons
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Answer: Atomic number
Mendeleev's original table used atomic mass, but the modern periodic table orders elements by atomic number (proton count).
A horizontal row in the periodic table is called a ___.
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Answer: period
Periods are horizontal rows. All elements in a period have electrons filling the same number of shells.
Which group of elements is the least reactive because their valence shells are full?
1. Alkali metals
2. Halogens
3. Noble gases
4. Alkaline earth metals
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Answer: Noble gases
Noble gases (Group 18) have 8 valence electrons — a full outer shell — making them extremely stable and unreactive.
The mass number of an atom equals its number of protons plus its number of neutrons.
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Answer: True
Mass number = protons + neutrons. For example, Carbon-12 has 6 protons + 6 neutrons = 12.
Carbon-12 and Carbon-14 are examples of:
1. Ions
2. Isotopes
3. Compounds
4. Alloys
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Answer: Isotopes
Isotopes are atoms of the same element (same proton count) with different numbers of neutrons, giving different mass numbers.
Metals are generally found on the ___ side of the periodic table.
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Answer: left
Metals occupy the left and center of the periodic table. Nonmetals are on the upper right, with metalloids forming the boundary.
How many valence electrons do halogens (Group 17) have?
1. 1
2. 2
3. 7
4. 8
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Answer: 7
Halogens have 7 valence electrons. They need just one more to complete their outer shell, which is why they are highly reactive.

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