Electron ve charged particle Outside of nucleus Thomsons discovery Mass 911 x 10 28 g Charge 176 x 10 8 C coulombs Proton ve charged particle Inside nucleus Rutherfords discovery ID: 414240
Download Presentation The PPT/PDF document "Subatomic Particles" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Subatomic ParticlesSlide2
Electron
-
ve
charged particle
Outside of nucleus
Thomson’s discovery
Mass = 9.11 x 10
-28
g
Charge = -1.76 x 10
8
C (coulombs)Slide3
Proton
+
ve
charged particle
Inside nucleus
Rutherford’s discovery
Mass = 1.67 x 10
-24
g (1836x heavier than electron)
Charge = +1.76 x 10
8
C (opposite electron)Slide4
Neutron
No charge
Inside nucleus
Chadwick’s Discovery
Mass of neutron = 1.67 x 10
-24
g (same as proton)
Charge = no chargeSlide5
Atomic Number
This is the number of protons in an atom
Hydrogen has 1 proton and thus is atomic number 1
Oxygen has 8 protons and thus atomic number 8
Every element is different due to its different numbers of protons
So changing the number of protons changes the element!
Some elements may have the same electrons (ions) or the same neutrons (isotopes)Slide6
Atomic Number
The atomic number is found on the bottom left corner
Atomic mass on the top left corner
Symbol in the middleSlide7
Atomic Number
Electrons counterbalance the charge of protons
So the number of electrons in a neutral atom is the same as the number of protons
When an electron is removed from a neutral atom
It becomes +
ve
because #protons > #electrons
When electron is added to a neutral atom
It becomes –
ve
as #protons < #electrons
Atoms with net charges are called ions
Net charge = #proton - #electronSlide8
Atomic Number
We show an ion exist by putting a +/- number on the top right corner of our element
NOTE! – Proton numbers do not change in ionsSlide9
Atomic Number
You try! Find the number of protons and electrons of the following
Uranium
Thallium
Tin
Lead
Mercury
Helium
YttriumSlide10
Atomic Mass
The mass of the atom
Atomic mass = #neutron + #protons
#neutron = atomic mass – atomic number
Oxygen has an atomic mass of 16. It has an atomic number of 8. To find the #neutron, we subtract the two.
16-8 = 8 neutrons
Gold’s atomic mass is 197 and atomic number is 79
#neutron = 197 – 79 = 118 neutronsSlide11
Atomic Mass
The electron is so light, it is only 1/1836 the mass of a proton and neutron that it does not contribute to the mass of the atom
We base all our atomic masses on the mass of carbon-12. The 12 stands for its atomic mass of 12.0000g/mol or
amu
(atomic mass unit)
1
amu
= 1.67 x 10
-24
g or the same mass as a neutron and protonSlide12
Atomic Mass
You try
, find the number of neutrons of the following. As well, what is the number of protons and electrons?
Plutonium
Einsteinium
Thorium
Gallium
Germanium
CaliforniumSlide13
Practice time!Slide14
Isotopes
As with ions, which is when we have different numbers of electrons
An isotope is where the number of neutron is different
Isotopes still have the same number of protons as the original atom
As they have different atomic masses due to the different number of neutrons, we write their names different.Slide15
Isotopes
We write the names with a hyphen and their mass
Carbon-12 = regular 12
amu
carbon
Carbon-13 = carbon with 1 extra neutron
Carbon-14 = carbon with 2 extra neutronsSlide16
Isotopes
When writing them in chemical symbol format, we drop the atomic number and just write the mass
16
O and
18
O
35
Cl and
37
ClSlide17
Isotopes
Lets take a look at hydrogen and its isotopes
Hydrogen-1 (
protium
)
99.985% of all hydrogen atoms
Most common element in our universe
Has 1 proton and o neutrons
Hydrogen-2 (deuterium)
Has 1 proton and 1 neutron
0.0167% of all hydrogen atoms
Used in nuclear reactors as heavy water D
2
O
Hydrogen-3 (tritium)
Has 1 proton and 2 neutrons
Used in hydrogen bombsSlide18
Isotopes
We can find the number of protons, neutrons, and electrons of an isotope as we would with a standard atom.
Just have to note the mass and that mass change is due to neutronsSlide19
Isotopes
You try finding the number of protons, neutrons, and electrons with the following
Uranium-238
Oxygen-18
Xenon-126
Hafnium-180Slide20
Average Atomic Mass
Why are all the masses of elements not whole numbers?
Why isn’t carbon 12.0000 and oxygen 16.00000 and chlorine just 35.00000 or 36.00000?
This is due to the masses in the periodic table being averages of all the masses of the isotopes based on abundanceSlide21
Example
Carbon-12 is 98.9% abundant in nature
Carbon-13 is 1.1% abundant in natureSlide22
Average Atomic Mass Steps to solve
Multiply each percentage as a decimal with the atomic mass
Add up all your decimals
This is your average atomic mass that shows up on the periodic tableSlide23
Example
Carbon-12 is 98.9% abundant in nature
Carbon-13 is 1.1% abundant in natureSlide24
Example
Nitrogen has an average atomic mass of 14.007. The two isotopes that make up nitrogen are nitrogen-14 and nitrogen-15. What are the percent abundance of each isotope?Slide25
Average Atomic Mass
You try
Chlorine is 75.8% chlorine-35 and 24.2% chlorine-37. What is the average atomic mass of chlorine?Slide26
Electron Arrangements
We look at electron arrangements in the form of Bohr modelsSlide27
Electron Arrangements
Each of the noble gases outer shells are full
They satisfy the octet rule
Outer shell electrons are also called “valence electrons”
Hence why the outer shell is usually called the valence shell
A full outer shell is stable, it doesn’t want to give or receive any more electronsSlide28
Remember!
1
st
Shell = 2 electrons
2
nd
Shell = 8 electrons
3
rd
Shell = 8 electrons
4
th
Shell = 18 electrons
-----------------------------------------------------------
5
th
Shell = 18 electrons
6
th
shell = 32 electrons
7
th
shell = 32 electronsSlide29
Remember!
You can remember this by counting across the periodic table.
The first row has 2 elements so 2 electrons
The second row has 8 elements so 8 electrons and so forth!Slide30
How do other elements gain stability?
Other elements do not have full outer shells as the noble gases do
They will try to lose or gain electrons to get to a full outer shellSlide31Slide32
How can we tell which will lose or gain electrons?Slide33
How can we tell which will lose or gain electrons?Slide34
Carbon stability?Slide35
Summary of element stabilitySlide36
Why does an element want to gain or lose electrons anyways?
Every element has an affinity for electrons
Affinity = attraction
Some elements have more affinity than others
We measure affinity and call it
electronegativity
The higher the
electronegativity
, the more the element wants electrons
Fluorine has the highest
electronegativity
Highest top right and weak bottom leftSlide37
So how does it work?
When two elements with differences in
electronegativity
come together, the one that is more electronegative draws the electron away from the less electronegative elementSlide38
vsSlide39
Homework
Page 146 #13-17
Page 147 #19
Page 149 #22
Page 150 #23 and 25
Worksheet on isotopes
Worksheet on atomic number