Periodic Trends

As you move down the periodic table, atoms get bigger. This is because ____________.

• The atoms have more mass.

• The atoms have more protons.

• The atoms have more energy levels.

• The atoms have more neutrons.

Answer explanation

As we move down the periodic table, atoms increase in size due to the addition of more energy levels, not because they have more mass, protons or neutrons. Each row on the table corresponds to a new energy level, so as we move down, more levels are filled with electrons, increasing the size of the atomic radius.

Tags

NGSS.HS-PS1-1

As you move across the periodic table, atoms tend to get smaller because ______________.

• The atoms have more mass.

• The atoms have less mass.

• The atoms have a larger effective nuclear charge (more protons)

• The atoms have fewer electrons.

Answer explanation

As we move across the periodic table, atoms indeed become smaller due to the increased effective nuclear charge. This increase in nuclear charge pulls the electrons closer to the nucleus, thereby reducing the size of the atom. None of the other options directly influence the size of atoms in the way that effective nuclear charge does.

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NGSS.HS-PS1-1

Which atom has the largest atomic radius?

• Potassium

• Rubidium

• Francium

• Cesium

Answer explanation

The atomic radius typically increases as we move down a group in the periodic table. This is due to the addition of energy levels. Francium is at the bottom of the 'alkali metal' group, implying that it has more energy levels and thus a larger atomic radius than potassium, rubidium, and cesium.

Which atom in Group 18 has the largest atomic radius?

• Ar

• He

• Kr

• Rn

Answer explanation

The atom with the largest atomic radius in Group 18 is Rn. The atomic radius increases as you move down a group in the periodic table because there are more energy levels, so the electrons are further away from the nucleus. As a result, Rn (Radon) has the largest atomic radius in Group 18.

Which of these has the largest atomic radius?

• Oxygen

• Fluorine

• Sulfur

• Chlorine

Answer explanation

In the periodic table, atomic radius tends to increase down a group due to the addition of new energy levels. So, among oxygen, fluorine, sulfur, and chlorine, sulfur has the largest atomic radius as it's lower down the group than the rest.

Which of these elements has the smallest atomic radius?

• C

• Ne

• K

• Al

• P

Answer explanation

The atomic radius usually increases as we move down a group in the periodic table because additional shells are being added. When moving across a period, the atomic radius decreases as the number of protons increases. Among the elements C, Ne, K, Al, and P, Neon (Ne) has the smallest atomic radius because it is furthest to the right and closest to the top of the periodic table among these options.

Tags

NGSS.HS-PS1-1

Atomic radius generally increases as we move __________.

• down a group and from right to left across a period

• up a group and from left to right across a period

• down a group and from left to right across a period

• up a group and from right to left across a period

Answer explanation

The atomic radius increases as we move down a group due to the addition of energy levels. It also increases from right to left across a period because the nuclear charge increases, which attracts the electrons of the outermost shell towards the nucleus and decreases the size of the atom. Thus, the atomic radius increases as we move down a group and from right to left across a period.

Tags

NGSS.HS-PS1-1

Which one has the largest radius?

• Lithium

• Boron

• Neon

• Nitrogen

Answer explanation

The question asks which among lithium, boron, neon, and nitrogen has the largest radius. The answer is lithium. This is because, in the periodic table, the atomic radius tends to decrease as you move across a period from left to right. Thus, lithium, being the first element among these options, has the largest radius.

Why does Cs have a larger radius than Na?

• It has more energy levels

• It has fewer energy levels

• It has a more effective nuclear charge

• It has a less effective nuclear charge

Answer explanation

Cs has a larger radius than Na because it has more energy levels. The number of energy levels increases as you move down the periodic table. Since Cs is below Na on the periodic table, it has more energy levels and therefore a larger atomic radius.

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NGSS.HS-PS1-1

Why does Ca have a larger radius than Se?

• Ca has more energy levels

• Ca has fewer energy levels

• Ca has a more effective nuclear charge

  (more protons)

• Ca has a less effective nuclear charge

  (Fewer Protons)

Answer explanation

Calcium (Ca) has a larger radius than Selenium (Se) because it has a less effective nuclear charge. This means that the pull from the nucleus on the outer electrons is weaker in Ca, allowing it to have a larger atomic radius.

Tags

NGSS.HS-PS1-1