Unit 2 Light and Electron Structure

Flashcard maker : Candace Young
the fundamental unit of which elements are composed
Dalton’s Atomic Therory

1. Elements are made up of tiny particle called atoms.

2. All atoms of a given element are identical. (**But it had to be changed to, “All atoms of the same element contain the same # of protons and electrons, but atoms of a given element may have different #’s of neutrons.”)

3. The atoms of a given element are different of those of any other element.

4. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms.

5. Atoms are indivisible in chemical processes. That is, atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.

Law of Constant Composition

A given compound always contains the same proportions (by mass) of the elements.;

Ex. Water always;contains 8g of oxygen for every 1g of hydrogen, and carbon dioxide always;contains 2.7g of oxygen for every 1g of carbon.

It means a given compound always has the same composition, regardless of where it comes from.

Atomic Structure

-Atoms are sphere like with an electron cloud around the outside of the atom.

-**When 2 atoms come together, the 1st thing that meets is their electrons.

-Contains a Nucleus

Nucleus: center of the atom, contains protons and neutrons, has a positive charge.

-Contains Protons

Protons: positive charge, amu: 1.0073, located in nucleus.

-Contains Neutron

Neutron: neutral charge, amu: 1.0087, located in nucleus.

-Contains Electron

Electron: negative charge, amu: .00055, located in outer shells, orbits around nucleus

Electron Cloud: 10x larger than the nucleus, the different electron clouds allow us to distinguish the atom and tell how much is present,;S-cloud: electrons moving in a spherical shaped cloud, P-cloud: electrons moving in a hour-glass shaped cloud-has a greater amount of energy than the S-cloud.

-they have the same # of protons but different #’s of neutrons
Atomic Number
-the # of protons in a nucleus
Mass Number

-the sum of protons and neutrons in a given nucleus




Layout of an Atom of an Element


                     23   <————mass #              Na       <——-Element symbol

           11   <————atomic #

Calculating the Atomic Mass using Isotopes

Ex:    Atom       Mass        %

        Ne-20      20.00      91%

Ne-22      22.00      9%

     Calculate the atomic mass!:

(.91 x 20.00) + (.09 x 22.00) = 20.18 amu


Ex:     24               25

     Mg        Mg

  12     12

   70.1%      29.9%


Calculate Atomic Mass!:

(.701 x 24) + (.299 x 25) = 24.299 amu

Aufbau Chart

**For filling electrons into the lowest energy level



2s   2p

3s   3p   3d

4s   4p   4d   4f

5s   5p   5d   5f  

6s   6p   6d

7s   7p



2s^2   2p^6

3s^2   3p^6   3d^10

4s^2   4p^6   4d^10   4f^14

5s^2   5p^6   5d^10   5f^14

6s^2   6p^6   6d^10

7s^2   7p^6


*This is the order in which the orbitals fill up. The letters that you see next to the numbers refer to the subshells of each orbit and they designate how many electrons can fit in those subshells. The capacity of each subshell is as follows:

s = 2
p = 6
d = 10
f = 14


Quantum #’s

a) ;n- principal quantum #, has integral values ; ; ; ; ; ; ; ;1,;2, 3…., region of space, called an energy ; ; ; ; ;level or shell

-gives energy level

b) ;l- azimuthal quantum #-defines by # the shape ; ; ; ; of the electron orbital (2 electron per orbital)


Leter: s ;p ;d ;f

;; ; #: 0 ;1 ;2 ;3

;; ; Orbitals: 1 ;3 ;5 ;7

;; Electrons: 2 ;6 ;10 14


n Value;; Possible l values;; Types of Orbitals

;; 1 0 1s

;; 2 0, 1 ;; ; ; ;2s, 2p

;; 3 0, 1, 2 ;; ; ; ;3s, 3p, 3d

;; 4 0, 1, 2, 3 4s, 4p, 4d, 4f


**Adding orbital with every energy level


c) ;m- magnetic quantum #, values -l to +l, gives ; ; ; ; ; ; orientation ; ; (names orbital)

-gives direction of orbital angular momentum


Ex: p is -1, 0, 1 for the 3 orbital types


d) ;s- spin around its axis can be clockwise or ; ; ; ; ; ; ; ; counter clockwise +1/2 or -1/2

-gives direction of spin


e) ;Hund’s Rule- electrons enter each orbital of a                          given type singly and with                                  identical spins before any pairing                          of electrons of opposite spin                                occurs


f) Aufbau Process- for filling electrons into the                                 lowest energy level


-S orbital: 1, so it can hold 2 electrons

-P orbital: 3, so it can hold 6 electrons

  -D orbital: 5, so it can hold 10 electrons

  -F orbital: 7, so it can hold 14 electrons


**only 2 electrons in 1 orbital

Energy Levels

-1st main energy level only has a single “s” sublevel. All s sub-levels contain 1 orbital and room for 2 electrons. Lowest energy state.


-2nd main energy level contains a 2 s and 2p (2 sublevels), with a total room for 8 electrons (2 in the 2s and 6 more in the 2p).


-3rd main energy level contains a 3s, 3p, and 3d sublevel  with room for 18 electrons (2 in the 3s, 6 in the 3p, and 10 in the 3d).


-4th main energy level starts off with the 4s orbital which is of lower energy than the 3d sublevel and therefore is filled to capacity before the 3d level.


-Remaining main energy levels all have s, p, d, and f sublevels and room for 32 electrons (2 in the s, 6 in the p, 10 in the d, and 14 in the f).


-Energy level 6 has 6 sublevels:


-the s, p, d, f sublevels are found in the 4th energy level

Electron Configurations

-Electron Configuration of an atom is the short hand representation of electrons in orbitals in which, especially the “outer shell” configuration, can give clues as to the atom’s chemical behavior.



-electromagnetic spectrum

-wavelength and color



-continuous spectrum

-bright line spectrum

-composed of a mixture of different colors

-travels in waves


-white light is composed of a mixture of lights of different colors

-a prism separate white light into those colors

-travels in waves

-each color has it’s own wavelength


-the shortest distance between equivalent points on a continuous wave;is usually expressed in meters, centimeters, or nanometers

-represented by (upside-down y-Greek Lambda)

-refers to the distance between two adjacent waves or two consecutive wave peaks


**Å– 1 x 10^10 A= 1m


Nm– 1 x 10^9nm= 1m

Electromagnetic Radiation

-a form of energy exhibiting wavelike behavior as it travels through space; can be described by wavelength, frequency, amplitude, and speed and includes visible light, microwaves, X rays, and radio waves

-energy is being transmitted from one place to another by light


-the # of waves that pass a given point per second

-represented by v (Greek nu)

-number of waves that pass a point per second unit (measure in Hertz or Hz)

-the # of waves that pass a given point in a specific time

-indicates how many wave peaks pass a certain point per given time period


-a particle of electromagnetic radiation with no mass that carries a quantum of energy

-a stream of tiny packets of energy

Ex: a photon of red light (relatively long wavelength) carries less energy than does a photon of blue light (relatively short wavelength)

-the minimum amount of energy that can be gained or lost by an atom
Heisenberg Uncertainty Principle
-states it is impossible to simultaneously determine  the velocity and position of an electron
Lewis Dot Diagrams

-can have 8 total dots

-give you the ability to determine the types of covalent bonds that an element may make in certain situations

-can also be used to predict the type of ion that an atom might make when it forms an ion

-each dot diagram consists of: an element symbol, and a group of 1-8 dots which show the configuration of the outer-most electron shell of the atom

-each side can only hold up to 2 dots 

Bright Line Spectrum

-an emission spectrum made up of bright lines on a dark background


Continuous Spectrum

-a spectrum in which all wavelengths are present between certain limits; it is produced by electrons undergoing free-bound transitions in a hot gas.


-White light for example can be dispersed by a prism to give a continuous spectrum in the optical region of the spectrum from red to violet. Dark absorption lines crossing a continuous spectrum are caused by the absorption of radiation at specific wavelengths

Pauli Exclusion Principle
-no two electrons in an atom can have identical quantum #’s
What happens to white light when it strikes an object that appears red to the eye?
-it absorbs the green and the blue energy of the spectrum and reflects the red energy to the observer.
What happens to white light when it strikes an object that appears black to the eye? What happens to the energy?
-No light is reflected when white light strikes a black object. The white light is absorbed and the energy of the object doing the absorbing is increasing. The energy also becomes absorbed, but the object releases the absorbed energy by transmitting longer wavelength, lower energy “infrared.” The electron moves to a higher energy level as it absorbs the energy.
Estimate the wavelength of red light in nm
-can range from 620-750nm’s
Convert nm to m by dimensional analysis

-1nm x 1m/1,000,000,000nm = 0.0000000001m

=1m = 1 x 10^9nm

Equation of Calculating the Frequency

C = (wavelength) * v

C-speed of light,

wavelength-upside down y              (Greek Lambda),



Ex: Calculate the frequency, v, of red light in              hertz, hz:


Equation of finding Energy

E = h * v


                             h-6.6 x 10^-34 joule/hz,



Ex: Calculate the energy of red light:

Periodic Table

-Each box on periodic table contains atomic mass, atomic #, and element symbol

periods go across the table

columns are the groups or families on the periodic table

noble gases are located on far right column, are unreactive, have filled s or p sublevel of electrons

alkali metals are located on far left of table, as you go down alkali metals column the elements become larger

-as you go down and across from right to left on table, the atomic radius gets larger

Demitry Mandelaum developed 1st periodic table

Hund’s Rule

-if you have more than one orbital in sublevel, only one electron in each orbital before pairing up

-electrons enter each orbital of a given type singly and with identical spins before pairing of electrons of opposite spin occurs


-negatively charged

-located in outer shells

-orbits around nucleus

valance:;outer shell of electrons

-electrons fill the lowest energy level 1st

-the lowest energy level is the 1s level

-no more than 2 electrons in one orbital

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