Exploring Atoms and Their Properties

Explain how the arrangement of electrons in an atom determines its position in the periodic table and its chemical properties.

• The number of protons determines the position, while electrons have no effect.

• The arrangement of electrons in shells and subshells determines the position and chemical properties.

• The number of neutrons determines the position, while electrons determine chemical properties.

• The atomic mass determines the position, while electrons determine chemical properties.

Answer explanation

The arrangement of electrons in shells and subshells determines an atom's position in the periodic table and its chemical properties, as it influences reactivity, bonding, and the types of elements it can interact with.

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DOK Level 3: Strategic Thinking

Analyze the trend in atomic radius as you move across a period from left to right in the periodic table. Explain the reasoning behind this trend.

• Atomic radius increases due to the addition of more electron shells.

• Atomic radius decreases due to increased nuclear charge pulling electrons closer.

• Atomic radius remains constant because the number of protons and electrons are balanced.

• Atomic radius increases due to increased electron-electron repulsion.

Answer explanation

As you move across a period, the atomic radius decreases due to increased nuclear charge from added protons. This stronger positive charge pulls the electrons closer to the nucleus, reducing the size of the atom.

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DOK Level 3: Strategic Thinking

Compare and contrast ionic and covalent bonds in terms of electron transfer and sharing. Provide examples to support your explanation.

• Ionic bonds involve sharing electrons, while covalent bonds involve transferring electrons.

• Ionic bonds involve transferring electrons, while covalent bonds involve sharing electrons.

• Both ionic and covalent bonds involve sharing electrons equally.

• Both ionic and covalent bonds involve transferring electrons equally.

Answer explanation

Ionic bonds involve the transfer of electrons from one atom to another, resulting in charged ions, while covalent bonds involve the sharing of electrons between atoms. For example, NaCl (ionic) vs. H2O (covalent).

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DOK Level 3: Strategic Thinking

Scarlett and Mason are conducting an experiment to evaluate the impact of temperature on the states of matter. They focus on the transition between solid, liquid, and gas.

• Increasing temperature always turns solids into gases directly.

• Increasing temperature causes solids to melt into liquids and liquids to evaporate into gases.

• Decreasing temperature causes gases to turn into solids directly.

• Temperature has no effect on the states of matter.

Answer explanation

Increasing temperature causes solids to melt into liquids and liquids to evaporate into gases, which accurately describes the transitions between states of matter during heating.

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DOK Level 3: Strategic Thinking

Samuel and Abigail are discussing how isotopes of an element differ and how this affects the calculation of atomic mass.

• Isotopes have different numbers of protons, affecting atomic mass.

• Isotopes have different numbers of neutrons, affecting atomic mass.

• Isotopes have different numbers of electrons, affecting atomic mass.

• Isotopes have the same number of neutrons, not affecting atomic mass.

Answer explanation

Isotopes differ in the number of neutrons, which changes their mass. Since atomic mass is calculated based on the total number of protons and neutrons, variations in neutrons directly affect the atomic mass of isotopes.

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DOK Level 3: Strategic Thinking

Predict how the electronegativity of elements changes as you move down a group in the periodic table and justify your prediction.

• Electronegativity increases due to increased atomic size.

• Electronegativity decreases due to increased atomic size.

• Electronegativity remains constant because the number of electron shells is the same.

• Electronegativity increases due to decreased atomic size.

Answer explanation

Electronegativity decreases as you move down a group because increased atomic size leads to greater distance between the nucleus and valence electrons, reducing the nucleus's ability to attract bonding electrons.

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DOK Level 3: Strategic Thinking

Samuel is observing the behavior of particles in different states of matter. Analyze the relationship between the kinetic energy of particles and the state of matter they are in.

• Particles in a solid have the highest kinetic energy.

• Particles in a gas have the highest kinetic energy.

• Particles in a liquid have the highest kinetic energy.

• All states of matter have the same kinetic energy.

Answer explanation

Particles in a gas have the highest kinetic energy because they move freely and rapidly compared to solids and liquids, where particles are more tightly packed and have less freedom to move.

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DOK Level 3: Strategic Thinking

Aria and Grace are discussing why some elements are more reactive than others. Critically evaluate the role of valence electrons in determining the chemical reactivity of an element.

• Valence electrons have no effect on chemical reactivity.

• The number of valence electrons determines the element's ability to form bonds.

• Valence electrons determine the element's atomic mass.

• Valence electrons determine the element's color.

Answer explanation

The number of valence electrons is crucial in determining an element's ability to form bonds, which directly influences its chemical reactivity. Elements with fewer or more valence electrons tend to react differently.

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DOK Level 3: Strategic Thinking

The periodic table is a chart that organizes the elements based on their atomic properties. Elements in the periodic table are organized according to the periodic law. The periodic law states that chemical and physical properties of elements are periodic functions of their atomic numbers (the number of protons in the nucleus). As the atomic number of elements increases, different elements display similar characteristics at regular intervals.

Periodic law states that elements are arranged _______________________________________________________________.

• in alphabetical order.

• from largest to smallest.

• as periodic functions of their atomic numbers.

• there is no rhyme or reason.

Answer explanation

Periodic law states that elements are arranged as periodic functions of their atomic numbers, meaning their chemical and physical properties recur at regular intervals as the atomic number increases.

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NGSS.HS-PS1-2

It stacks the elements in columns according to the number of valence electrons in an atom of the element. Valence electrons are those in the outermost shell of the atom and the ones that participate in reactions. The number of valence electrons is associated with the element’s reactivity. Elements with the same number of valence electrons behave in a similar way in reactions and so are grouped together in the same column on the periodic table.

What does the amount of valance electrons determine about an element?

• Its row in the table.

• Its atomic number.

• Its atomic mass.

• Its reactivity with other elements.

Answer explanation

The amount of valence electrons determines an element's reactivity with other elements. Elements with the same number of valence electrons exhibit similar chemical behavior, which is why they are grouped in the same column on the periodic table.