Topic Test: Atomic Structure and Chemical Bonding

Which of the following scientists used a cathode ray to demonstrate the existence of negatively charged subatomic particles called electrons?

• JJ Thomson

• Ernest Rutherford

• Niels Bohr

• John Dalton

Answer explanation

JJ Thomson is well known for his cathode ray experiment in which he observed the ray be deflected by a magnet. This suggested that the ray was composed of a negatively charged particle proving the existence of electrons.

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FL.SC.912.P.8.3.

Match the model with the the scientists theory that inspired it.

• Thomson's Theory

• 
• Rutherford's Theory

• 
• Dalton's Theory

• 
• Bohr's Theory

• 
• Schrodinger's (Current) Theory

• 

Answer explanation

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FL.SC.912.P.8.3.

Explain how Ernest Rutherford's gold foil experiment provided evidence that atoms have a nucleus and are mostly empty space. Your response should address the 2 key findings of the experiment and how they led to the understanding of atomic structure. Please write one well-organized paragraph. (+1 for explaining the empty space, +1 for explaining the nucleus, +1 for proper grammar and spelling)

Answer explanation

1 point for mentioning that alpha particles can only go straight through the gold foil if atoms are mostly empty space

1 point for mentioning that alpha particles that were deflected could only happen if they had hit the nucleus

1 point for using proper grammar and vocabulary

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FL.SC.912.P.8.3.

Match each subatomic particle with the correct charge

• Positive

• Electron

• Negative

• Neutron

• Neutral

• Proton

Answer explanation

Protons are positive subatomic particles found in the nucleus with the neutral neutrons. Electrons are negatively charged and are found in the electron cloud orbiting the nucleus.

Tags

FL.SC.912.P.8.4.

True or False: The charge of an atom is neutral if the number of protons equals the number of neutrons.

• False

• True

Answer explanation

Neutrons are neutral so they do not contribute to the overall charge of an atom. When protons (positive) and electrons (Negative) are present in equal amounts the atom is neutral.

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FL.SC.912.P.8.4.

The mass number is composed by adding the number of _______ and _______.(Must select only 2 answers)

• Protons

• Neutrons

• Electrons

Answer explanation

Protons and neutrons have similar masses while electrons are massless by comparison. So adding the mass of the proton and neutrons encompasses the atomic mass.

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FL.SC.912.P.8.4.

Rank the fundamental forces from STRONGEST to WEAKEST (Left/Strongest/1 to Right/Weakest/4)

• Electromagnetic Forces

• Weak Nuclear Force

• Gravity

• Strong Nuclear Force

Answer explanation

The strong nuclear force (SNF) is the strongest force we know of that binds protons and neutrons together in the nucleus. Following that is electromagnetism that has a strength that is 1/137 of the SNF and helps binds electrons to the positively charged nucleus. The weak nuclear force is 1/1000000 the strength and is what leads to nuclear decay. The gravitational force is 10-41 strength of the SNF and its the attraction between larger masses.

Tags

FL.SC.912.P.10.10.

What fundamental force is responsible for binding protons and neutrons together in the nucleus?

• Strong Nuclear Force

• Weak Nuclear Force

• Gravitational Force

• Electromagnetic Force

Answer explanation

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FL.SC.912.P.10.10.

What fundamental force is responsible for binding electrons with the positively charged nucleus?

• Strong Nuclear Force

• Weak Nuclear Force

• Gravitational Force

• Electromagnetic Force

Answer explanation

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FL.SC.912.P.10.10.

Which of the following elements is considered a noble gas?

• Neon (Ne)

• Florine (F)

• Sodium (Na)

• Calcium (Ca)

Answer explanation

Group 18 (or 8A) elements are the main group elements known as the noble gases. They have a full outer shell (8 electrons with Helium being the exception with 2 electrons) thus have no need to form any bonds with any other element to have an octet. Based off the octet rule we know each elements wants to have a full outer shell so will either exchange electrons or share them to form bonds. Noble gases again, have no need to do this.

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FL.SC.912.P.8.5.