Atomic Structure questions

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Atomic Structure question collection

Review Atomic Structure questions for Chemistry, with correct answers shown and coverage across protons, neutrons and electrons; atomic number and mass number; isotopes and relative atomic mass.

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Question 1

What is the smallest part of an element that can still be that element?
  1. An atom
  2. A molecule
  3. A compound
  4. A mixture

Question 2

What is a substance made of only one type of atom called?
  1. An element
  2. A compound
  3. A mixture
  4. An isotope pair

Question 3

Which formula represents a compound?
  1. CO2
  2. O2
  3. N2
  4. Ar

Question 4

Where are electrons found in an atom?
  1. In shells around the nucleus
  2. Inside the nucleus with protons
  3. Only in the outermost layer of all atoms
  4. Mixed with neutrons in the center

Question 5

Which subatomic particle has a positive charge?
  1. Proton
  2. Electron
  3. Neutron
  4. Isotope

Question 6

Which subatomic particle has no charge?
  1. Neutron
  2. Proton
  3. Electron
  4. Nucleus

Question 7

In a neutral atom, the number of protons equals the number of which particle?
  1. Electrons
  2. Neutrons
  3. Shells
  4. Isotopes

Question 8

What does atomic number tell you?
  1. The number of protons
  2. The number of neutrons
  3. The total number of particles in the nucleus
  4. The number of electron shells

Question 9

Mass number is found by adding together?
  1. Protons and neutrons
  2. Protons and electrons
  3. Neutrons and electrons
  4. Electrons and shells

Question 10

An isotope of an element has a different number of which subatomic particle?
  1. Neutrons
  2. Protons
  3. Electrons in a neutral atom
  4. Outer shells

Question 11

The periodic table is arranged in order of increasing?
  1. Atomic number
  2. Mass number
  3. Number of isotopes
  4. Reactivity only

Question 12

What are the vertical columns in the periodic table called?
  1. Groups
  2. Periods
  3. Series
  4. Families of compounds

Question 13

What are the horizontal rows in the periodic table called?
  1. Periods
  2. Groups
  3. Blocks
  4. Series of isotopes

Question 14

Why do elements in the same group have similar chemical properties?
  1. Outer-shell electrons
  2. Neutrons
  3. Protons in total
  4. Electron shells overall

Question 15

Group 0 elements are usually very unreactive because they have?
  1. A full outer electron shell
  2. No electrons
  3. No neutrons
  4. A very high mass number

Question 16

Most metals are found on which side of the periodic table?
  1. Left-hand side
  2. Right-hand side
  3. Only in the middle row
  4. Only in Group 0

Question 17

Why did Mendeleev leave gaps in his periodic table?
  1. To leave space for elements not yet discovered
  2. He had not measured atomic masses
  3. He grouped atoms by color
  4. He only included metals

Question 18

What did the gold foil scattering experiment show about atoms?
  1. Atoms are mostly empty space with a small, dense nucleus
  2. Atoms are solid spheres all the way through
  3. Electrons are in the nucleus
  4. Nuclei are negatively charged

Question 19

A lithium atom has 3 protons and 4 neutrons. What is its mass number?
  1. 7
  2. 3
  3. 4
  4. 12

Question 20

Which pair correctly matches symbol and element?
  1. Na - sodium
  2. S - silicon
  3. Cl - calcium
  4. Mg - manganese

Question 21

Which statement about atom structure is correct?
  1. Almost all the mass is concentrated in the nucleus
  2. Most of the mass is in electron shells
  3. Protons orbit around electrons
  4. Neutrons are negatively charged

Question 22

Which experiment provided evidence for the nuclear model of the atom?
  1. Alpha particle scattering by thin gold foil
  2. Electrolysis of copper sulfate
  3. Flame tests with metal ions
  4. Simple distillation of crude oil

Question 23

An atom has atomic number \(12\) and mass number \(24\). How many neutrons does it have?
  1. \(12\)
  2. \(24\)
  3. \(6\)
  4. \(36\)

Question 24

For chlorine isotopes \(35\) (\(75\%\)) and \(37\) (\(25\%\)), what is the relative atomic mass?
  1. \(35.5\)
  2. \(36.0\)
  3. \(35.0\)
  4. \(36.5\)

Question 25

What is the electronic structure of sodium (atomic number \(11\))?
  1. \(2,8,1\)
  2. \(2,8,2\)
  3. \(2,7,2\)
  4. \(2,9\)

Question 26

What is the electronic structure of calcium (atomic number \(20\))?
  1. \(2,8,8,2\)
  2. \(2,8,8,1\)
  3. \(2,8,10\)
  4. \(2,10,8\)

Question 27

Why do elements in the same group have similar reactions?
  1. They have the same number of outer-shell electrons
  2. They have the same number of neutrons
  3. They all have the same mass number
  4. They have identical numbers of shells

Question 28

What charge does a sodium ion have after losing one electron?
  1. \(+1\)
  2. \(-1\)
  3. \(+2\)
  4. \(0\)

Question 29

What is the electron arrangement of a chloride ion, Cl-?
  1. \(2,8,8\)
  2. \(2,8,7\)
  3. \(2,7,8\)
  4. \(2,8,8,1\)

Question 30

What is the approximate radius of an atom?
  1. \(1 \times 10^{-10}\,\mathrm{m}\)
  2. \(1 \times 10^{-6}\,\mathrm{m}\)
  3. \(1 \times 10^{-14}\,\mathrm{m}\)
  4. \(1 \times 10^{-2}\,\mathrm{m}\)

Question 31

The nucleus has a radius of about \(1 \times 10^{-14}\,\mathrm{m}\). Compared with the atom, this is roughly?
  1. \(\frac{1}{10{,}000}\) of the atomic radius
  2. \(\frac{1}{10}\) of the atomic radius
  3. The same size as the atom
  4. \(10\) times larger than the atom

Question 32

What is the relative mass of an electron compared with a proton?
  1. Very small, about \(\frac{1}{1836}\)
  2. Exactly \(1\)
  3. About \(1836\)
  4. Exactly \(0\)

Question 33

How does Group 1 reactivity change down the group?
  1. It increases
  2. It decreases
  3. It stays constant
  4. It alternates every element

Question 34

How does Group 7 reactivity change down the group?
  1. It decreases
  2. It increases
  3. It stays constant
  4. It doubles each period

Question 35

Why are Group 0 elements unreactive?
  1. Their outer electron shells are full
  2. They have no electrons
  3. They have no protons
  4. They all have low melting points only

Question 36

Which halogen can displace bromine from potassium bromide solution?
  1. Chlorine
  2. Iodine
  3. Astatine
  4. Neon

Question 37

What was the key limitation of Dalton's early atomic model?
  1. It did not include subatomic particles
  2. It included too many electron shells
  3. It showed a full nuclear model
  4. It predicted isotopes accurately

Question 38

A sample has \(60\%\) isotope X-\(20\) and \(40\%\) isotope X-\(22\). What is the relative atomic mass?
  1. \(20.8\)
  2. \(21.0\)
  3. \(20.0\)
  4. \(22.0\)

Question 39

Aluminium-\(27\) forms Al3+. How many electrons are in Al3+?
  1. \(10\)
  2. \(13\)
  3. \(14\)
  4. \(27\)

Question 40

What is the best explanation of why scientific models of the atom changed over time?
  1. New experimental evidence led to revised explanations
  2. Chemists voted to change models without evidence
  3. Models changed only because of better drawing tools
  4. Atomic models never changed after Dalton

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Review Atomic Structure questions for Chemistry, with correct answers shown and coverage across protons, neutrons and electrons; atomic number and mass number; isotopes and relative atomic mass.

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