Unit 3 - The AtomLesson 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 – Quantum Numbers and Electron Configurations

An atomic orbital is the __________________________ in which there is a high probability of finding an

__________________.

Quantum NumbersEach electron must have a different location (atomic orbital) in the atomThe electrons are described by four quantum numbers.

1.

2.

3.

4.

Principal Quantum Number

___________________where the electron is located

Numbered 1 to 7 out from the NucleusEach level holds a maximum of ___________ number of electrons

Principal level 1 holds _______ electrons

Principal level 2 holds _______ electrons

Principal level 3 holds _______ electrons

Principal level 4 holds ________electrons

These energy levels correspond to the ________________ on the periodic table

Angular Momentum Quantum Number

Electrons also occupy _________________________ within each level. These sublevels are given the designations ____________________________.

These designations are in reference to the ________________________________________________ lines in emission spectra. Shapes of the atomic orbital include: __________________________________________________________________________________.

The number of _______________ in each level is the _____________ as the number of the main level (up to four sublevels).

Energy Level: Can Have Shapes:

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 orbitals 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 ________________________________________.

Assigning the _____________________ in atom

Use only ___________________ and __________________ quantum numbers

Electron Configurations and the Periodic Table

The periodic table can be used as a __________________________________________.

The period number is the value of _______________.

Groups 1A and 2A have the ________________ filled. Groups 3A - 8A have the _______________ filled.

Groups 3B - 2B have the ________________ filled. The lanthanides and actinides have the ____________ filled.

Blocks and Sublevels

We can use the periodic table to ________________________________________ by a particular element.

Diagonal Method

Writing electron configurationsWrite configurations for O, Ni, Br, Sr

O=

Ni=

Br=

Sr=

Exceptions to the AUFBAU principle

Chromium prefers a _______________ as opposed to a ________________, thus 4s13d5

Copper prefers a _________________ as opposed to a ________________, thus 4s13d10

This _______________, or ___________ d orbital, is used most of the time to explain this, but other transition metals do not follow this trend.

AUFBAU exceptions of ______________________________ as a half full _______________ are

____________________ than a full 4 s sublevel, or for copper that a full d-sublevel is

________________ than a half full 4s

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.

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