Unit 4B
4.4 – The Periodic Table
Background
Different scientists organized the elements differently—this lead to confusion
In 1869, Dimitri Mendeleev designed a periodic table based on ______.
This way showed ______in properties that repeated across rows and similarities down columns
He couldn’t find elements to fit all the property trends, so he left holes
The holes he left were later filled in as more elements were discovered
The modern periodic table is arranged by ______rather than atomic mass
This caused a few “switches” in placement, but overall is very similar to Mendeleev’s
- Henry Mosley is given credit for the modern periodic table.
- Modern Periodic Law: ______
Organization
Rows (going horizontal, across the periodic table) are called “______”
Columns (going vertical, down the periodic table) are called “______” or “______”
______Whole number – this is how the elements are ordered (equal to the number of protons)
______1st letter is ALWAYS capital, if there is a second letter it is ALWAYS lowercase
______usually with decimals; gives the mass, in grams, for 1 mole of atoms. THIS IS NOT THE MASS NUMBER!
Color in the :
Metals (blue)
Metalloids or semi-metals (green)
Nonmetals(yellow)
Most periodic tables are written with 2 rows at the bottom.
This is done to allow the font to be bigger on a piece of paper but they really belong in between groups 2 and 3!
Properties of Metals
All solid except for mercury
Formability
______: can be flattened into thin sheets
______: can be drawn into fine wire
Great conductors of heat & electricity
High luster
High strength
Properties of NonMetals
Mostly ______, few solids and 1 liquid, Br
Poor formability
Poor conductors of heat & electricity
dull
brittle
Properties of Metalloids/Semi metals
share properties of both metals & nonmetals
All solids
Semiconductors
Electron Configuration Patterns on the Periodic Table
Look at the electron configurations for the Halogens
F 1s2 2s2_____
Cl 1s2 2s2 2p6 3s2_____
I 1s2 2s2 2p6 3s2 3p6 4s2 3d10_____
Br1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10_____
All of the elements in Group 7 end with ______in a p subshell
In fact, every Group ends with the ______of electrons in the highest energy subshell
2 Types of Elements
Representative elements: Group A
See special families info.
Transition Elements: Group B
Have more than 1 ______
Typically the ______reactive of the metals
Hardest, densest, and highest melting points
Greatest conductors of heat and electricity
Families of Representative Elements
Group 1A: Alkali Metals
Most ______metals; always found in compound form
Reacts violently with water to produce hydrogen gas and a ______
Soft and silver in color
Low density & ______
1 valence electron and forms +1 ions
Group 2A: Alkaline Earth Metals
less reactive than 1 A but still extremely reactive; always found in compound form
Reacts with water to produce hydrogen gas and a base – Not Explosive
Extracted from ______-mineral rocks
Harder,higher density & melting points than 1A
______valence electron and forms +2 ions
Group 7A: Halogens
most reactive ______; always found in compound form
Most form the ______molecules
7 valence electrons and forms -1 ions
Group 8A: Noble Gases
non-reactive elements- most ______
Called inert gases
8 valence electrons and does not form ions
Other important facts
Hydrogen is a diatomic ______& in a group by itself; can have a +1 or -1 charge
Lanthanides: 1st row of lower block; called ______metals
Actinides: 2nd row of lower block; all are ______and most are man-made
4.5 Trends & Periodicity
What is periodicity?
Diagram of Atomic Radius
Trend 1: Atomic Radius
Atomic radius is defined as:
Period (horizontal trend) : ______
Why? As the number of protons increase, the ______increases.
As the nuclear charge ______, the attraction between the positive nucleus and negative electron cloud increases
Group(vertical trend): ______
Why? the electrons are added in new ______.The inner electrons “shield” the new outer electrons from the pull of the ______therefore it doesn’t pull as strongly.
Examples:
List the following in INCREASING order of atomic radius . Li Cs K
List the following in DECREASING order of atomic radius . Ca Be Ba Sr
Who has the largest atomic radius? Mg Cl, Na P
Trend 2: Ionization Energy
Ionization Energy is defined as:
Period (horizontal trend) : ______
Why? Moving left to right, the ______of the atom decreases as more protons pull on more electrons.When an atom is ______, the electrons are ______to the nucleus, and therefore feel the pull more strongly. THUS it is harder to pull electrons away from these smaller atoms
Group(vertical trend): ______
Why? As you move down a group, the radius increases as more ______are added. As the outer electrons (those involved in bonding) are farther from the ______, they will feel the “pull” of the nucleus ______. Thus it is easier to remove an electron from a larger atom.
Examples:
List the following in INCREASING order of ionization energy . Li Cs K
List the following in DECREASING order of ionization energy . Ca Ba Be Sr
Who has the highest ionization energy? Cl Na I In
Successive Ionization Energies” means the energy required to remove a 2nd or a 3rd electron from an atom.
Removing more and more e-’s requiresmore & more energy.
Why? The remaining e-’s are more tightly bound to the nucleus.
Trend 3: Electronegativity
Electronegativity is defined as:
______is the highest ____ is the lowest
Period (horizontal trend) : ______
Why? When an atom is smaller, the ______pulls more strongly.This can attract & draw an electron ______from another atom.
Group(vertical trend): ______
Why? The larger atom is less able the nucleus is to ______electrons away from another atom.
Examples:
Who has the highest electronegativity . Ba Br Ca
List the following in decreasing order of electronegativity . I, Cl, Br
Trend 4: Ionic Radii & Charge
An ion is defined as:
Cations are ______ions resulting from a metal ______electrons.
Anions are ______ions resulting from a nonmetal______electrons
Cations are smaller than neutral atoms!
Why?When electrons are lost, there are now more ______than electrons. Therefore, the protons have a ______“pull ” on each of the electrons.
Anions are larger than neutral atoms!
Why? When electrons are gained, there are now more ______than protons. Therefore, the protons have a ______“pull” on each of the electrons.
Period (horizontal trend) : ______
Group(vertical trend): ______
***** Notice it’s the same trend as atomic radii!****
Examples:
Arrange in order of decreasing ionic radius. P-3 Mg+2 Cl-1
Arrange in order of increasing ionic size: K+1 Cs+1 Li+1
Trend 5: Reactivity
Reactivity is defined as:
For Metals
Period (horizontal trend) : ______
Group(vertical trend): ______
Why? The more reactive metals have the ______ionization energy
For NonMetals
Period (horizontal trend) : ______
Group(vertical trend): ______
Why? The most reactive nonmetals have the ______ionization energy and electronegativity
4.6 Light
Electromagnetic radiationis all ______that exhibits wavelike behavior and travels through space.
Examples are: ______
All energy travels at the speed of light which equals ______
Electromagnetic Spectrum (EM spectrum)
Identifies all forms of electromagnetic radiation
Wave Properties
______() is the distance from trough to trough of a wave (measured in meters “m”)
______() is the number of times a wave completes a cycle in one second (cycles per second is “Hertz” or “Hz”)
Notice that the shorter the wavelength, the ______the frequency. This is a ______relationship
Using the EM SPECTRUM above, notice as frequency increases, the amount of energy ______. This is a ______proportional relationship.
The ______is a small region within the spectrum that has wavelengths/frequencies that are eyes can detect.
ROY G BIV is a mnemonic to help you remember the colors of the spectrum. Red is near ______and violet is near ultra violet.
Examples using Reference Sheet
- Which of the following forms of electromagnetic radiation has the shortest wavelength?
a) gammab) visiblec) infraredd) radio
- As the frequency of electromagnetic radiation increases, its wavelength ______.
a) increasesb) decreasesc) remains constantd) is impossible to determine.
- Which of the following forms of radiation has photons with greatest amount of energy?
a) red lightb) yellow lightc) green lightd) violet light
- What type of electromagnetic radiation is represented by a wavelength of 1870 nm?
a) infraredb) visible lightc) ultravioletd) x-ray
- What type of electromagnetic radiation is represented by a wavelength of 4.7x10-1 m?
a) gamma raysb)infraredc)microwavesd) visible light
4.7 Light & Matter
Continuous Spectrum: Sunlight (or white light) will produce a ______of color because there are no ______wavelengths.
Line Spectrum is when ______atoms emit light of only certain ______. Each element has its own line spectrum.
How can a line spectrum be explained?
Energy packets called ______or quanta come in contact with an atom and collide with an electron
EXCITATION: this is the process of an electron ______a photon of light and being promoted to a higher energy level from its ______state
The electron cannot remain in the excited state indefinitely SO
RELAXATION: the process of an electron ______the photon of light it absorbed and falling back down to a lower energy level.
The higher the Energy of a photon, the greater the jump. For example, a photon of ______light would have more energy than infared light so there would be a higher jump. See diagram below.
The TOTAL ENERGY IN = TOTAL ENERGY OUT
If an atom absorbs a large photon of energy that moves it up 2 energy levels, it will release the exact same amount of energy but it can be released in smaller packets moving the electron back down in ______manner.
The energy of the photon must ______match the energy change of an electron. If it does not match, the energy passes through the electron with no change.
Hydrogen Line Spectrum: The colored lines are the wavelengths of light that were emitted when the electron’s moved from a higher to a lower energy level. The blue line is a result of the electron moving from the 4th to the 2nd energy level.
Bohr’s study of light gave him the proof that atoms had fixed energy levels.
Examples using the Reference Sheet
- On the energy level diagram below, draw an arrow representing the electron in hydrogen’s ground state being excited to the fourth energy level.
2. An electron in the hydrogen atom makes the transition n = 5 n = 3.
- Determine the wavelength of light associated with this transition. Include units.
a) 434 nmb) 434 mc) 1282 nmd) 1282 m
- Classify the type of electromagnetic radiation this wavelength represents:
a) infraredb) visible lightc) ultravioletd) x-ray
- Is this energy emitted by the atom or absorbed by the atom? ______
Flame Tests
______can be identified by the wavelength of light they emit. When metals absorb energy from a flame, the ______absorb energy and are raised to higher energy level. When they return to their______, they release the energy they absorbed in the form of radiation. The wavelength of light for some metals fall in the ______light portion of the spectrum. This allows us to see their color.
Ways of producing Light
- Fluorescence: visible light is absorbed and visible light is emitted at the same time—the relaxation happens very quickly after excitation
- Phosphorescence: Visible light is absorbed and then a while later is emitted—relaxation occurs after a period of time
- Incandescence: Energy is put in from heat and given off as visible light
- Chemiluminescence: Energy released during a chemical reaction is absorbed to cause excitation. Relaxation produces visible light
- Biolouminescence: Chemiluminescence that occurs in a biological organism.
- Triboluminescence: Physical pressure or torque provides energy for excitation. Relaxation produces visible light.