ca-inspire-chemistry-sampler

COLLECT EVIDENCE

Use your Science Journal to

record the evidence you collect as

you complete the readings and

activities in this lesson.

INVESTIGATE

GO ONLINE

to find these activities and more resources.

Virtual Investigation: Electron Configuration

Obtain, evaluate, and communicate information on

the patterns

present in the periodic

table that translate into patterns of electron states.

Laboratory: Electron Charge-to-Mass Ratio

Analyze and interpret data

to determine the

proportion

of charge to mass for an electron.

Disciplinary Core Ideas

Crosscutting Concepts

Science & Engineering Practices

3D THINKING

Ground-State Electron Configuration

The arrangement of electrons in an atom is called the atom’s

electron configuration.

Because low-energy systems are more stable than high-energy systems, electrons in an

atom tend to assume the arrangement that gives the atom the lowest energy possible.

The most stable, lowest-energy arrangement of the electrons is called the element’s

ground-state electron configuration.

Three rules, or principles—the aufbau

principle, the Pauli exclusion

principle, and Hund’s rule—define

how electrons can be arranged in an

atom’s orbitals.

The aufbau principle

The

aufbau principle

states that each

electron occupies the lowest energy

orbital available. Therefore, your first

step in determining an element’s

ground-state electron configuration is

learning the sequence of atomic

orbitals from lowest energy to highest

energy. This sequence, known as an

aufbau diagram, is shown in

Figure 18

In the diagram, each box represents

an atomic orbital.

FOCUS QUESTION

How are electrons arranged in atoms?

LESSON 3

ELECTRON CONFIGURATION

C05_030A

Orbital filling sequence

Increasing energy

Figure 18

The aufbau diagram shows the energy of each sublevel

relative to the energy of other sublevels.

Determine

Which sublevel has the greater energy, 4d or 5p?

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Module 4 • Electrons in Atoms