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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