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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).