Subatomic Particles and Isotopes
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Transcript Subatomic Particles and Isotopes
Subatomic Particles and
Isotopes
Subatomic Particles
Protons- Positively Charged
Located in the nucleus
Have the same mass as a neutron
Have same but positive charge of an electron
Atomic number tells number of protons in an
atom of that element
Atomic Number = # protons
Example- Carbon atomic number= 6
Has 6 Protons
Neon- Atomic Number ?
# protons ?
Electrons
Negative charge
In the electron cloud
Smaller than protons and neutrons
Has the same charge as protons, but it is
negative
In a neutral atom, # protons= #electrons
Electrons
In a neutral atom, # protons= #electrons
If electrons ≠ protons, the atom has a charge
Known as an ion
If more protons- atom has a positive charge
If more electrons- atom has a negative charge
To find the charge:
charge= protons - electrons
Neutrons
Neutrally charged
Located in nucleus
Have the same mass of protons
For most atoms, # protons=#neutrons
However, for some atoms
#protons ≠ #neutrons
These are called isotopes
Isotopes
#protons ≠ #neutrons
Mass number= #protons + #neutrons
What is the mass number of carbon with 8
neutrons?
Answer: 14
Written: carbon- 14
Isotopes
How many neutrons does hydrogen-3 have?
Answer: 2
mass #= #protons + #neutrons
3
=
1
+
# neutrons
3–1
=
#Neutrons
Why are isotopes important?
They contribute to the mass of the atom.
Why?
Most of the mass of the atom is from protons and
neutrons
If there is an additional neutron the mass
increases
Also, they have properties different from
other isotopes
Carbon-14
The Average Atomic Mass
The average of the masses of all the
isotopes of an atom
That’s why the average atomic mass is a
decimal!
Average Atomic Mass
Tells you the most abundant isotope of an
atom.
Example- Iron (Fe)
Average atomic Mass: 55.845
Round the mass to the nearest whole number
55.845 round to 56
Iron- 56 is the most abundant isotope of iron
Determine the Most Abundant
Isotopes for the Following
Elements
1.
2.
3.
4.
5.
6.
Lithium (Li)
Carbon
Oxygen
Hydrogen
Neon
Chlorine
•Lithium- 7
•Carbon- 12
•Oxygen- 16
•Hydrogen- 1
•Neon- 20
•Chlorine- 35 and Chlorine36