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’s in the Nucleus?The nucleus contains 2 of the 3 subatomic particles:

Protons: _________________ charged subatomic particles (______________________)

Neutrons: _________________ charged subatomic particles (______________________)

What’s in the Electron Cloud?The 3rd subatomic particle resides outside of the nucleus in the __________________.

Electron: the subatomic particle with a _____________________ and relatively _________________.

Parts of an atom

Subatomic 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 does the information on the Periodic Table tell me?

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 isotopesThe 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 neutronsA =

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.

Finding average atomic massEven though it is the least massive, Ne- 20 accounts for the vast majority of Neon.

Isotope Mass Abundance Mass Contribution

Ne-20

Ne-21

Ne-22

Avg. mass =

ExamplesGallium-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 Contribution

Ga-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?

Isotope Mass Abundance Mass Contribution

Tl-203

Tl-205

Avg. mass =

Lesson 3 : The Bohr ModelBohr 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.

This is called the __________________________

When an e- ________________________ (loses) energy it falls ______________________

____________ 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.

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=________

PracticeWhat 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 ____________________________________________________________.

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 _____.

Radiant Energy Spectrum

The complete ______________________________________ is an uninterrupted band, or

________________________________________.

The radiant energy spectrum includes __________________________, most of which are ____________ to the human eye.

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

Wave/Particle Nature of Light:

In 1900, Max Planck proposed that radiant energy is not continuous, but is _________________________.

This is the ________________________.

Radiant energy has _________________________________________________________.

An individual unit of light energy is a ________________.

Electromagnetic Spectrum (EM)EM is the complete range of __________________________________________.

WavelengthFrequencyEnergy

Wave Nature of Light

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

____________________ is the distance light travels in one cycle.

_____________________ is the number of wave cycles completed each second.

As frequency ___________________, energy ________________

Small ___________________ = Large ___________________ = Big ______________________

Anatomy of a Wave

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

Amplitude – the ______________________________________________________________________

Frequency ( ν ) – the ___________________________ that pass a given point in ____________________

Inverse Relationship Between Wavelength(λ) and Frequency (ν)

When λ _____________, ν _____________. When λ _____________, ν _____________.

When ν _____________, λ _____________. When ν _____________, λ _____________.

The longer the ___________________ of light, the lower the ___________________. The shorter the

___________________of light, the higher the ___________________.

Lesson 4 – Electron Configurations

Principal Quantum Number

___________________where the electron is located

These energy levels correspond to the ________________ on the periodic table

Electrons 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

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 PrincipleGives 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 Configurations

The ___________________________ 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.

If the 2p sublevel contains 2 electrons, it is written _______________.

The electron sublevels are ________________________________________.

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 Electrons

Valence 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 e- configurationsSince 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

K=

Shorthand practiceWrite the shorthand electron configuration of:

P

Br

Ca

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:

Hund’s Rule

Within a sublevel, place __________________ before pairing them.

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).