Unit 3 - The Atom

NC Essential Chemistry Standards:Chm.1.1 Analyze the structure of atoms and ions. Chm.1.1.1 Analyze the structure of atoms, isotopes, and ions. Chm.1.1.2 Analyze an atom in terms of the location of electrons.Chm.1.1.3 Explain the emission of electromagnetic radiation in spectral form in terms of the Bohr model.Chm.1.3 Understand the physical and chemical properties of atoms based on their position on the Periodic Table.Chm.1.3.2 Infer the physical properties (atomic radius, metallic and nonmetallic characteristics) of an element based on its position on the Periodic Table.

Lesson 1 – Subatomic particles

What is an atom?Atom: the __________________________________ that retains the identity of the substance.

An atom is made of __________________, __________________,

and __________________.

Atomic StructureAtoms are composed of 2 regions:1. ___________________: the ____________ of the atom that

contains the ___________ of the atom

2. ____________________: region that ____________________

that contains _____________________ in the atom

What is in the Nucleus?The nucleus contains 2 of the 3 subatomic particles:

Protons: _________________ charged subatomic particles

(______________________)

Neutrons: _________________ charged subatomic particles

(______________________)

What is in the Electron Cloud?The 3rd subatomic particle resides in the __________________.

Electron: the subatomic particle with a _____________________ and

relatively _________________.

Parts of an atomSubatomic

Particle Charge Mass Location

Proton

Neutron

Electron

How do these particles interact?

________________________ are compacted in the tiny positively

charged nucleus accounting for most of the _______________of the

atom but barely any _________________.

The negatively charged _______________________ are small and

have a relatively small ________________ but occupy 99% + of the volume of the atom.

How do the subatomic particles balance each other?In a neutral atom:

The protons =

If __________________ are present in an atom then

____________________ are there to balance the overall charge of

the atom—atoms are ____________________, meaning they have

an overall charge of __________________.

The neutrons have _______________________; therefore they ________________ have to equal the number of protons or electrons.

How do we know the number of subatomic particles in an atom?

Atomic number (Z): this number indicates the __________________ in an atom.

Ex: Hydrogen’s atomic number is 1How many protons does H have?

Ex: Carbon’s atomic number is 6How many protons does C have?

**The number of protons _______________ the atom as a specific

____________________.

Ex. 2 protons = ____________, 29 protons = _____________

How do we know the number of subatomic particles in an atom?

Mass number (A): the number of _______________ &

___________________ in the nucleus

Ex: hydrogen can have a mass of 3.Since it has 1 proton it must have ____________________.

# of neutrons =

What information can I get from the Periodic Table?

Determining the number of protons and neutrons

Li has a mass number of ______ and an atomic number of ________.

Protons = Neutrons=

Ne has a mass number of ______ and an atomic number of _______.

Protons = Neutrons =

What about the electrons?In a neutral atom, the ____________ are equal to the number of

___________

So e- = p =

Ex: He has a mass # of 4 and an atomic # of 2

p+ = no = e- =

Determine the number of subatomic particles in the following neutral atoms:

Cl has a mass # of 35 and an atomic # of 17

p+ = no = e- =

K has a mass # of 39 and an atomic # of 19

p+ = no = e- =

Lesson 2 - Isotopes

Different Forms of the Same Element

In any specific element, the # of _________________ is always

____________.

Unlike the number of protons, the number of

__________________________________ can vary within

_______________of an element ___________________changing the identity of the element.

Ex. Carbon (C) ALWAYS has ______________, but it can have

anywhere from ________________ and ____________________

IsotopesIsotopes: atoms of the __________________ (same number of

____________) but with different number of _______________

Carbon has three isotopes:

Notice how the __________ does NOT change but the mass number does.

Determining the atomic mass of isotopes* The atomic mass on the periodic table is an _______________ of all the known isotopes of each element.

* It is not the mass of any ______________________________.

* To determine the mass of a specific isotope you need to add the

number of __________________ to the number of

_____________________. This is _______________________.

Practice A lithium atom has 3 protons, 3 electrons, and 3 neutrons.

A =

A nitrogen atom has 8 neutrons

A =

An unknown element has 92 protons and 143 neutrons.

Element = A =

Representing IsotopesOption # 1: Top number is ___________________, bottom number

is _____________________.

U

K

C

Option #2: Only the ___________________ is listed, the

_________________ can be found on the _____________________.

U –

K –

C –

Finding average atomic massTo find the average atomic mass of an element you need two pieces of information:

1. The ______________________ of the different isotopes

(this is NOT the __________________ found on the periodic table)

Ex.

2. The _________________________ of each isotope

Ex.

Even though it is the least massive, Ne- 20 accounts for the vast majority of Neon.

Examples

Gallium-69 has a relative abundance of 60.11% and Gallium-71 has a relative abundance of 39.89%. What is the average atomic mass of Gallium?

Isotope Mass Abundance Mass ContributionGa-69

Ga-71

Avg. mass =

Thallium has two stable isotopes, Thallium-203 and Thallium-205. Thallium-203 has a relative abundance of

29.52%.Thallium-205 has a relative abundance of70.48%. What is the average atomic mass of Thallium?

Lesson 3: The Bohr Model

Bohr Model of an Atom

Electrons orbit the _____________ in fixed energy ranges called

________________

An electron can move from one energy level to another by

______________________ discrete amounts of energy.

Electrons __________________ be found between energy levels (think of energy levels like rungs on a ladder)

The lowest energy

level is ____________to the nucleus, the

highest is ____________ away.

The electron energy levels are

_______________________.

Absorption Vs EmissionWhen an electron (e-) _____________________ (gains) energy

(in whole photons or “quanta”) it _________________________ to a higher energy level.

Isotope Mass Abundance Mass ContributionNe-20Ne-21Ne-22

Avg. mass =

Isotope Mass Abundance Mass Contribution

Tl-203

Tl-205

Avg. mass =

This is called the ____________________

When an e- _____________ (loses) energy it falls to a

_______________ energy level and the energy emission is given of as photons (light)

This is called the ___________________________

The return to ______________________ is what we see as color in the flame test.

So how was the “color” made in the flame test? Scientists use the

______________________ to explain this phenomenon

There is NO net change in energy

Energy absorbed = = energy of light produced

Sometimes (like the flame test) this light is in the small section of

wavelengths called the

_________________________ and we can see it. Most of the time the human eye cannot.

Interpreting Bohr’s Hydrogen Model

Turn to page 8 in your ref. packetWhen an electron falls from n=6 to n=3 what wavelength of light will be emitted?

What region of the spectrum does that wavelength correspond to?

Would we see it?

Hydrogen’s Line SpectrumHydrogen emits ____________________________ wavelengths of light.

Visible light is emitted when an _______________ electron “falls”

from n= _____________ back to n=________

Practice

What color of light will be emitted if an e- goes from:

n=6 to n=2?

n=5 to n=2?

n= 3 to n=2?

Evidence for Energy Levels

Bohr realized that this was the _________________________he

needed to prove his _________________________.

The electric charge ____________________________________

__________________________. When the electron drops back

down, a ________________________.

The red line is the __________________________ and corresponds

to an electron dropping from energy level ____ to energy level ____.

Electromagnetic Spectrum (EM)EM is the complete range of ______________________________

________________________________________.

The spectrum includes __________________________, most of

which are ____________ to the human eye.

The ___________________________________ is the range of wavelengths between 400 and 700 nm.

Wavelength

FrequencyEnergy

Anatomy of a Wave

Wavelength ( λ ) – ___________________________________on a continuous wave. Wavelength is measured is units of length - m, mm, µm, nm

Amplitude - ______________________________________to the

__________________________.

Frequency ( ν ) – the ___________________________ that pass a

given point in ____________________

Wave Nature of Light

Light travels through space as a _______________, similar to an ocean wave.

As frequency ___________________, energy ________________

(_________________ relationship)

Wavelength (λ) and frequency (ν) have an _________ relationship….

As λ ______________, ν _________________.

*Short ___________ = High _____________ = High ____________

*Long ___________ = Low _____________ = Low ____________

Wave/Particle Nature of Light:In 1900, Max Planck proposed that radiant energy is not continuous,

but is _________________________.

This is the ________________________.

Radiant/Light energy has _________________________________

____________________.

An individual unit of light energy is a ________________.

Lesson 4 – Electron Configurations

Principal Quantum Number

__________________where the electron is located

These energy levels correspond to the ________on the periodic table

SublevelsElectrons also occupy __________________within each level. These sublevels are given the designations s, p, d, and f.

The number of sublevels in each Principal Quantum Number is the same as the number of the main level (up to four sublevels).

Principal Energy Level Sublevel(s)

1

2

3

4-7

Electron Occupancy in Sublevels

The ____________________________________ in each of the energy sublevels depends on the sublevel:

The s sublevel holds a maximum of ______________.

The p sublevel holds a maximum of ______________.

The d sublevel holds a maximum of ______________.

The f sublevel holds a maximum of _______________.

The ____________________ per level is obtained by adding the

________________________ in __________ sublevel.

Aufbau Principle

Gives the order in which __________________________ are filled

Electrons occupy the sublevels of _________________________ first

The Periodic Table is a guide for the Aufbau Principle, going from left to right as you move down the periodic table

Each element represents one _____________________, each period

(row) represents one __________________________.

Electron ConfigurationsThe ___________________________ of an atom is a method of

writing the _______________________ by sublevel.

The _______________ is written followed by a _________________ with the number of electrons in the sublevel.

The electron sublevels are arranged in order of _________________

___________________.

Write configurations for Hydrogen through Neon

H

He

Li

Be

B

C

N

O

F

Ne

Write configurations for Ni, Br, Sr

Ni

Br

Sr

Valence ElectronsValence Electrons = electrons in an atom’s ____________________

______________ (furthest from ____________).

When an atom undergoes a chemical reaction, only the

______________________________ are involved.

These electrons are generally further from the nucleus are of the

_______________________ and determine the _________________

__________________________ of an element -- they are the

“__________________” electrons to chemists.

Each element can have a maximum of _________valence electrons.

(Except _________ has 2 and ___________________ CAN have 2.)

Shorthand/Noble Gas e - configurations Since the valence electrons are the “________________” electrons,

we use a _______________________ to show an elements valence electrons.

All ________________________ (family 18) have 8 valence electrons and there for have a very stable configuration (most atoms want ________ valence electrons)

Electron Configuration ShorthandWrite configurations for K and Ar

K

Ar

Write configuration for K using shorthand/Noble Gas

K

Shorthand practiceWrite the shorthand/Noble gas electron configuration of:

P

Br

Ca

V

Ar

K

P

BrCa V

Orbital DiagramsAn __________________ is the region of space where there is a

__________________________ of finding an atom.

The higher the energy of an orbital, the _____________________.

Each atomic orbital has a box (_____________________________)

Hund’s Rule:

Nitrogen Orbital Diagram:

Electron Diagram ProblemWrite the orbital diagram and determine the number of unpaired electrons for iron.

Electron Dot StructuresBecause valence electrons are so important in the ____________

__________________, chemists represent them visually using another shorthand method.

An ________________________________ consists of an atoms symbol surrounded by dots that represent the atoms

___________________________.

Example : Carbon _______________________ has 4 valence

electrons

Rules for adding the “dots”Place valence electrons one at a time on all four sides of the symbol,

then (if needed) __________________________ up until all have been used.

Exception: Helium has a full valence shell with 2 electrons

PracticeIn the space below, draw the electron dot structures for:

Sr F Na

S Si Al

P Xe

Summary: Write the standard electron configuration, shorthand configuration, orbital diagram, and electron dot structure for Germanium (Ge).