Ch. 13: Electrons in Atoms

Standards: PS2B

Targets:• Deduce the electron arrangement for

atoms and ions.• Explain how the lines in an emission

spectrum are related to electron energy levels.

Deduce the electron arrangement for atoms and ions.

Models of ElectronArrangement

• J. J. Thomsen (1856-1940) Negatively charged electrons stuck into a lump of positively charged material. Plum Pudding Model

• Neils Bohr (1885-1962)

Electrons arranged in circular paths, or orbits, around the nucleus. Planetary Model

• Erwin Schrodinger (1887-1961) Used mathematics (quantum theory) to describe the location and energy of an electron. Quantum Mechanical Model

Deduce the electron arrangement for atoms and ions.

(Just read this slide, don’t write)

The Quantum-Mechanical Model. Electrons are not found at certain distances from the

nucleus but are located in a region in space that is described by a set of 4 quantum numbers. The exact location and path of the electron can’t be determined.

It estimates the probability of finding an electron within a certain volume of space surrounding the nucleus. Electron positions can be represented by a fuzzy cloud surrounding the nucleus (electron cloud).

Deduce the electron arrangement for atoms and ions. (write BOLD)

1st Quantum Number: energy level (n): Describes how far the electron is from the nucleus

These levels are assigned values in order of increasing energy:(n=1,2,3,4,…). The larger the number, the more energy the electrons have and are farther from the nucleus.

Each of the energy levels is divided into sublevels.

• n=1 has 1 sublevel• n=2 has 2 sublevels• n=3 has 3 sublevels and so

on

chemwiki.ucdavis.edu

Deduce the electron arrangement for atoms and ions. (write Bold)

2nd Quantum Number: energy sublevel (l): Describes the shape of the space the electron can be found in

Sublevel Shapes:• s: spherical shape; 1s, 2s, 3s, 4s, 5s

…• p: dumbbell-shaped; 2p, 3p, 4p, 5p

…• d: clover-leaf shape or double

dumbbell; 3d, 4d, 5d …• f: funky shape; 4f, 5f, …

There are more sublevels but we won’t use them. Each energy level contains n number of sublevels

• n=1 has 1 sublevel (s)• n=2 has 2 sublevels (s,p) • n=3 has 3 sublevels (s,p,d)• n=4 has 4 sublevels (s,p,d,f)• n=5 has 5 sublevels (s,p,d,f,?)

chemwiki.ucdavis.edu

Deduce the electron arrangement for atoms and ions. (Write BOLD)

3rd Quantum number: orbitals (m)Describes how many different arrangements in space thesublevels can have.

• Every s sublevel has 1 position• Every p sublevel has 3 positions• Every d sublevel has 5 positions • Every f sublevel has 7 positions

1s has 1 position; 2p has 3 positions, 4p has 3 positions; 3d has 5 positions; 5f has 7 positions Meta-synthesis.com

Deduce the electron arrangement for atoms and ions. (write BOLD)

4th quantum number: spin (s)Any orbital can only have a

maximum of two electrons, each having opposite spins.

(this is like the pigs in the “Hog Hilton”)

• Every s sublevel can only have a maximum of 2 electrons

• Every p sublevel can only have a maximum of 6 electrons

• Every d sublevel can only have a maximum of 10 electrons

• Every f sublevel can only have a maximum of 14 electrons

Chegg.com

Deduce the electron arrangement for atoms and ions. (Write BOLD)

Order of Electron “Fill-up”

This order must be followed every time

1s, 2s, 2p, 3s, 3p, 4s, 3d,4p, 5s, 4d, 5p, 6s, 4f, 5d,

6p, 7s, 5f, 6d, 7p

Pass out Electron Road Map

Energy Level Summary

n = energy level

l = sublevel

m =orbital

s = spin

4p

4 = energy level

p = sublevel; there are 3 orbitals/rooms available

6 = number of electrons; 2 electrons fit in each orbital

Deduce the electron arrangement for atoms and ions.

Diagramming Electron Arrangement

There are three methods for diagramming electronArrangement

• Electron Configuration• Orbital Filling Diagram• Electron Dot Diagram

Deduce the electron arrangement for atoms and ions.

Orbital Filling

1. Determine number of electrons in the atom.2. Draw a box or a line for each orbital. 3. Place arrows to denote electrons. Maximum of 2

electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each orbital must get an electron before the second electron is added

How many electrons do each of the following elements have?

• H• Be • O

Deduce the electron arrangement for atoms and ions.

Orbital Filling

1. Determine number of electrons in the atom.2. Draw a box or a line for each orbital. 3. Place arrows to denote electrons. Maximum of 2

electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each orbital must get an electron before the second electron is added

How many electrons do each of the following elements have?

• H: 1 e-

• Be: 4 e- • O: 8 e-

Deduce the electron arrangement for atoms and ions.

Orbital Filling

1. Determine number of electrons in the atom.2. Draw a box or a line for each orbital. 3. Place arrows to denote electrons. Maximum of 2

electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each orbital must get an electron before the second electron is added

Draw orbital filling diagrams for the following atoms.

• H __ 1s

• Be __ __ 1s 2s

• O __ __ __ __ __ 1s 2s 2p

Deduce the electron arrangement for atoms and ions.

Orbital Filling

1. Determine number of electrons in the atom.2. Draw a box or a line for each orbital. 3. Place arrows to denote electrons. Maximum of 2

electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each orbital must get an electron before the second electron is added

Draw orbital filling diagrams for the following atoms.

• H __ 1s

• Be __ __ 1s 2s

• O __ __ __ __ __ 1s 2s 2p

Deduce the electron arrangement for atoms and ions.

Orbital Filling

Draw a box or line for each orbital. Place arrows to denote electrons. Maximum of 2 electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each orbital must get an electron before the second electron is added

Draw orbital filling diagrams for the following atoms.

• Al

• Ca

• Zr

Deduce the electron arrangement for atoms and ions.

Orbital Filling

Draw a box or circle or line for each orbital. Place arrows to denote electrons.

Maximum of 2 electrons per box. The first arrow is pointing up, the second

arrow is pointing down to represent opposite spins. Within a sublevel, each

orbital must get an electron before the second electron is added

Draw orbital filling diagrams for the following atoms.

• Al __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p

• Ca __ __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p 4s

Deduce the electron arrangement for atoms and ions.

Orbital Filling

Draw a box or circle or line for each orbital. Place arrows to denote electrons.Maximum of 2 electrons per box. The first arrow is pointing up, the second arrow is pointing down to represent opposite spins. Within a sublevel, each

orbital must get an electron before the second electron is added

Draw orbital filling diagrams for the following atom.

• Zr __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p __ __ __ __ __ __ __ __ __ 4s 3d 4p __ __ __ __ __ __ 5s 4d

Go to orbital filling practice (electron Configuration (level one) Handout.

Deduce the electron arrangement for atoms and ions.

Electron Configuration

Start with 1s and follow the order until all the electrons in

the atom have a place.

Draw electron configurations for the following elements:H 1s1

Be 1s22s2

O 1s22s22p4

AlCaZr

Deduce the electron arrangement for atoms and ions.

Electron Configuration

Start with 1s and follow the order until all the electrons in

the atom have a place.

Draw electron configurations for the following elements:H 1s1

Be 1s22s2

O 1s22s22p4

Al 1s22s22p63s23p1 Ca 1s22s22p63s23p64s2

Zr 1s22s22p63s23p64s23d104p65s24d2

GO TO ELECTRON CONFIGURATION PRACTICE (Level 2)

Deduce the electron arrangement for atoms and ions.

Electron Dot Diagram Using the symbol for the element, place dots around the symbol

correspondingto the outer energy level s & p electrons (valence electrons). Will

have fromone to eight dots in the dot diagram.

Draw electron dot diagrams for the following atoms

H Be O Al Ca Zr

H Be O

Deduce the electron arrangement for atoms and ions.

Electron Dot Diagram Using the symbol for the element, place dots around the symbol

correspondingto the outer energy level s & p electrons. Will have from one to eight

dots inthe dot diagram.

Draw electron dot diagrams for the following atoms

Al Ca Zr

Deduce the electron arrangement for atoms and ions.

Electron Dot Diagram Using the symbol for the element, place dots around the symbol

correspondingto the outer energy level s & p electrons. Will have from one to eight

dots inthe dot diagram.

GO TO ELECTRON DOT DIAGRAM HODraw electron dot diagrams for the following atoms

Al Ca Zr

Al Ca Zr

Deduce the electron arrangement for atoms and ions.

Write electron configuration, orbital filling diagrams, and electron dot diagrams.

Cl Sn Tb Kr

Explain how the lines in an emission spectrum are related to electron

energy levels.Electromagnetic Spectrum• Shows all electromagnetic

waves by frequency and wavelength

• Visible light is the portion we can see (ROY G BIV)

• UV, x-rays, and gamma rays are more energetic than visible light (smaller wave length)

• Radio, TV, radar, and infrared rays are less energetic than visible light (longer wave length)

Explain how the lines in an emission spectrum are related to electron

energy levels.Continuous Spectrum

Emission showing a continuous range of

wavelengths and frequencies

Line SpectrumEmission of specific elementsshowing a series of discrete

lines

Explain how the lines in an emission spectrum are related to electron

energy

What is happening?• When atoms absorb

energy, electrons move into higher energy levels.

• The atom becomes unstable so the electrons then lose energy by emitting light, or photons, when they return to lower energy levels.

Explain how the lines in an emission spectrum are related to electron

energy

Atomic Spectra and Frequency• Each line of light in an element’s atomic spectra is a

specific frequency of light emitted by the atoms of that element.

Explain how the lines in an emission spectrum are related to electron

energy• Different elements have different atomic spectra

because their electrons make different energy transitions between their energy levels

Explain how the lines in an emission spectrum are related to electron

energy

Hydrogen Line Spectrum (must know this one!)• Purple, Blue, Green, Red• Note the spacing of the lines!• Draw this in your notes!

Deduce the electron arrangement for atoms and

ions.Ion Electron Configurations

What are ions?Atoms with a charge (more or less e-)Anion: atom with a negative charge (gained e-)Cation: atom with a positive charge (lost e-)

How will this change electron configurations?It will add or subtract electrons

Deduce the electron arrangement for atoms and

ions.Electron Configurations

H 1s1

Be 1s22s2

O 1s22s22p4

Al1s22s22p63s23p1

P1s22s22p63s23p3

Ion Electron Configurations

H+ 1s0

Be2+ 1s2

O2- 1s22s22p6

Al3+ 1s22s22p6

P3-

1s22s22p63s23p6

Deduce the electron arrangement for atoms and

ions.Ion Electron Configurations

Practice:

Write the electron configurations for the following ions:

Li+, I-, Ra2+, S2-, N3-

Deduce the electron arrangement for atoms and ions.

Ion Orbital FillingOrbital Filling diagrams for atoms:

• Al __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p

• Ca __ __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p 4s

Orbital Filling for ions:• Al3+ __ __ __ __ __ __ __ __ __

1s 2s 2p 3s 3p

• Ca2+ __ __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p 4s

Atomic Spectra and Electron Energy

• Each line of light is equal to a specific amount of energy given off as a result of electrons moving from higher to lower energy levels.

Atomic SpectraThe frequencies of light emitted by an element separate into discrete lines to give the atomic emission spectrum of the element.

Mercury Nitrogen

*The light emitted by an electron moving from a higher to a lower energy level has a frequency directly proportional to the energy change of the electron.

When light from a helium lamp passes through a prism, discrete lines are produced.

An Explanation of Atomic Spectra

In the Bohr model, the lone electron in the hydrogen atom can have only certain specific energies.

–When the electron has its lowest possible energy, the atom is in its ground state.

–Excitation of the electron by absorbing energy raises the atom from the ground state to an excited state.

–A quantum of energy in the form of light (photon) is emitted when the electron drops back to a lower energy level.

Hydrogen spectraExact amounts of energy are absorbed by H as electrons move to higher energy levels

The same amount of energy absorbed is emitted as the electrons fall back to the lower energy levels

The energy is emitted in the form of light with a frequencies that contain the energy being lost as the electrons move to the lower levels