Unit Topic: Atomic Structure

Josh and Luke are discussing famous scientists and their contributions to the atomic model. Which of the following correctly matches a scientist with their contribution to the discovery of the structure of the atom?

• John Dalton - Plum Pudding Model

• J.J. Thomson - Discovery of the Electron

• Ernest Rutherford - Quantum Mechanical Model

• Niels Bohr - Discovery of the Neutron

Answer explanation

J.J. Thomson is correctly matched with the discovery of the electron, which he identified in 1897. The other options incorrectly attribute contributions to the wrong scientists.

Mayson and JJ are discussing different models of the atom. Mayson explains that one model depicts electrons in fixed orbits, while JJ describes another model that shows electrons in probabilistic clouds. Which models are they referring to?

• The Bohr Model depicts electrons in fixed orbits, while the Electron Cloud Model shows electrons in probabilistic clouds.

• The Bohr Model shows electrons in probabilistic clouds, while the Electron Cloud Model depicts electrons in fixed orbits.

• Both models depict electrons in fixed orbits.

• Both models show electrons in probabilistic clouds.

Answer explanation

The Bohr Model represents electrons as being in fixed orbits around the nucleus, while the Electron Cloud Model illustrates electrons as existing in probabilistic clouds, indicating their likely positions rather than fixed paths.

Jacob and Mayson are discussing the structure of an atom. Can you summarize their understanding by explaining the two main parts of an atom, where the three subatomic particles are located, and where the mass and volume in an atom mainly exist?

• Atoms consist of a nucleus and electron cloud; protons and neutrons are in the nucleus, electrons in the cloud; mass is in the nucleus, volume in the electron cloud.

• Atoms consist of a nucleus and electron cloud; electrons and neutrons are in the nucleus, protons in the cloud; mass is in the electron cloud, volume in the nucleus.

• Atoms consist of a nucleus and electron cloud; protons and electrons are in the nucleus, neutrons in the cloud; mass and volume are equally distributed.

• Atoms consist of a nucleus and electron cloud; all particles are in the nucleus; mass and volume are in the nucleus.

Answer explanation

The correct choice accurately describes atomic structure: protons and neutrons are in the nucleus, electrons are in the electron cloud. Most of the atom's mass is concentrated in the nucleus, while the volume is primarily in the electron cloud.

Josh and Luke are discussing what holds an atom together. What are the three forces at work that keep an atom intact?

• Gravitational, electromagnetic, and weak nuclear forces

• Electromagnetic, strong nuclear, and weak nuclear forces

• Gravitational, strong nuclear, and electromagnetic forces

• Strong nuclear, weak nuclear, and gravitational forces

Answer explanation

The correct answer is 'Electromagnetic, strong nuclear, and weak nuclear forces' because these three forces are essential in holding an atom together: the strong nuclear force binds protons and neutrons, while electromagnetic forces hold electrons in orbit.

Tags

NGSS.HS-PS2-4

Jacob and Mayson are discussing elements in their chemistry class. Jacob asks Mayson: Which numbers tell you the following: a. The number of protons in an element b. The number of protons and neutrons in an element c. The number of total electrons d. The identity of an element e. The most common form of an element

• a. Atomic number, b. Mass number, c. Atomic number, d. Atomic number, e. Atomic mass

• a. Mass number, b. Atomic number, c. Mass number, d. Mass number, e. Atomic number

• a. Atomic mass, b. Atomic number, c. Atomic mass, d. Mass number, e. Mass number

• a. Atomic number, b. Atomic mass, c. Mass number, d. Mass number, e. Atomic number

Answer explanation

The atomic number indicates the number of protons (a), the mass number is the sum of protons and neutrons (b), and the atomic number also represents total electrons (c) and the identity of the element (d). The atomic mass reflects the most common form (e).

Jacob and Josh are discussing what it means for an atom to be electrically neutral. Can you explain it to them?

• An atom has more protons than electrons.

• An atom has more electrons than protons.

• An atom has an equal number of protons and electrons.

• An atom has no protons or electrons.

Answer explanation

An atom is electrically neutral when it has an equal number of protons and electrons. Protons are positively charged, and electrons are negatively charged; their balance results in no overall charge.

Mayson and Josh are discussing isotopes of an element. Mayson explains that two isotopes of the same element have something in common and something different. Can you help them understand what two isotopes of the same element have in common and what is different about them? Also, explain when an isotope is considered to be the most stable.

• Two isotopes of the same element have the same number of protons but different numbers of neutrons. The most stable isotope is the one with the lowest energy state.

• Two isotopes of the same element have different numbers of protons but the same number of neutrons. The most stable isotope is the one with the highest energy state.

• Two isotopes of the same element have the same number of electrons but different numbers of protons. The most stable isotope is the one with the highest energy state.

• Two isotopes of the same element have different numbers of electrons but the same number of neutrons. The most stable isotope is the one with the lowest energy state.

Answer explanation

Two isotopes of the same element share the same number of protons but differ in neutrons. The most stable isotope is the one with the lowest energy state, making the first answer choice correct.

Tags

NGSS.MS-PS1-1

JJ and Luke are discussing the most common isotope for lithium in their chemistry class. Write in both hyphen and nuclear notation the most common isotope for lithium.

• The most common isotope for lithium is Lithium-7 (7Li) in nuclear notation and 7Li in hyphen notation.

• The most common isotope for lithium is Lithium-6 (6Li) in nuclear notation and 6Li in hyphen notation.

• The most common isotope for lithium is Lithium-8 (8Li) in nuclear notation and 8Li in hyphen notation.

• The most common isotope for lithium is Lithium-9 (9Li) in nuclear notation and 9Li in hyphen notation.

Answer explanation

The most common isotope of lithium is Lithium-7, represented as 7Li in both nuclear and hyphen notation. Lithium-6 and Lithium-8 are less common, while Lithium-9 is not a stable isotope.

Imagine JJ and Dwipp are discussing the structure of the electron cloud. JJ asks Dwipp to explain how many electrons are held on each level, where valence electrons are, and which electrons are the craziest.

• The electron cloud is structured in energy levels with specific electron capacities, valence electrons are in the outermost level, and electrons in higher energy levels are the most energetic.

• The electron cloud is a random distribution of electrons, valence electrons are in the innermost level, and electrons in lower energy levels are the most energetic.

• The electron cloud has no specific structure, valence electrons are scattered randomly, and all electrons have the same energy.

• The electron cloud is structured in energy levels with equal electron capacities, valence electrons are in the middle level, and electrons in lower energy levels are the most energetic.

Answer explanation

The correct choice explains that the electron cloud is organized into energy levels with specific capacities, valence electrons are in the outermost level, and electrons in higher energy levels are the most energetic.

Tags

NGSS.HS-PS1-2

Jacob and Mayson are discussing why elements in the same group of the periodic table have similar properties. What is the reason for this similarity?

• Because they have the same number of protons.

• Because they have the same number of neutrons.

• Because they have the same number of electrons in their outer shell.

• Because they have the same atomic mass.

Answer explanation

Elements in the same group have similar properties because they possess the same number of electrons in their outer shell. This similarity in valence electrons leads to comparable chemical behavior and reactivity.