a scientist is measuring the momentum of electrons produced in a cathode-ray tube; however, she notices that the more accurately she determines the momentum of the electrons the less sure she can be of their position.

• periodic principle

• aufbau principle

• uncertainty principle

• Pauli exclusion principle

A chemist reacts chlorine gas with potassium to form potassium chloride, which consists of K+ and Cl- ions. Which of the following properties of chlorine is most important in this reaction? electron ?

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NGSS.HS-PS1-2

An element will be attracted by a magnet if atoms of the element contain unpaired electrons. Oxygen atoms have four electrons in their 2p subshells and are weakly attracted by magnets.

• quantum theory of light

• theory of relativity

• Hund's rule

• periodic law

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This "rule" of Quantum Chemistry states that no 2 electrons in an atom can be in the exact same state...each electron in an atom can be described by a unique set of quantum numbers.

• Hund's Rule

• Heisenberg Uncertainty Principle

• Aufbau Principle

• Pauli Exclusion Principle

According to the Aufbau Principle, which sublevel should starting filling with electrons before the 3p sublevel?

• 3s

• 2p

• 4s

• 4p

The NOBLE GAS electron configuration of chlorine can be written as

• [Ne]3s²3p⁵

• 1s²2s²2p⁶3s²

• 1s²2s²2p⁶3s²3p⁵

• [He]3s²3p⁵

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How many quantum numbers are needed to describe the energy state of an electron in an atom?

• 1

• 2

• 3

• 4

Using noble-gas notation, calcium is represented by [Ar]4s². How many electrons does calcium have?

• 18

• 20

• 22

• 24

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Which element is represented by this orbital notation?

• carbon

• nitrogen

• oxygen

• fluorine

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What is the total number of energy levels used by an atom of aluminum
(Al, atomic #13) in the ground state?

• 3

• 7

• 13

• 0

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