1. Subatomic Particles and Isotopes

2. Subatomic Particles Protons- Positively Charged Protons- Positively Charged Located in the nucleus Located in the nucleus Have the same mass as a neutron Have the same mass as a neutron Have same but positive charge of an electron Have same but positive charge of an electron Atomic number tells number of protons in an atom of that element Atomic number tells number of protons in an atom of that element Atomic Number = # protons Atomic Number = # protons Example- Carbon atomic number= 6 Example- Carbon atomic number= 6 Has 6 Protons Has 6 Protons Neon- Atomic Number ? # protons ? Neon- Atomic Number ? # protons ?

3. Electrons Negative charge Negative charge In the electron cloud In the electron cloud Smaller than protons and neutrons Smaller than protons and neutrons Has the same charge as protons, but it is negative Has the same charge as protons, but it is negative In a neutral atom, # protons= #electrons In a neutral atom, # protons= #electrons

4. Electrons If electrons ≠ protons, the atom has a charge If electrons ≠ protons, the atom has a charge Known as an ion Known as an ion If more protons- atom has a positive charge If more protons- atom has a positive charge If more electrons- atom has a negative charge If more electrons- atom has a negative charge To find the charge: To find the charge: charge= protons - electrons charge= protons - electrons

5. Neutrons Neutrally charged Neutrally charged Located in nucleus Located in nucleus Have the same mass of protons Have the same mass of protons For most atoms, # protons=#neutrons For most atoms, # protons=#neutrons However, for some atoms However, for some atoms #protons ≠ #neutrons These are called isotopes These are called isotopes

6. Isotopes #protons ≠ #neutrons #protons ≠ #neutrons Mass number= #protons + #neutrons Mass number= #protons + #neutrons What is the mass number of carbon with 8 neutrons? What is the mass number of carbon with 8 neutrons? Answer: 14 Answer: 14 Written: carbon- 14 Written: carbon- 14

7. Isotopes How many neutrons does hydrogen-3 have? Answer: 2 mass #= #protons + #neutrons 3=1+# neutrons 3 – 1=#Neutrons

8. Why are isotopes important? They contribute to the mass of the atom. They contribute to the mass of the atom. Why? Why? Most of the mass of the atom is from protons and neutrons Most of the mass of the atom is from protons and neutrons If there is an additional neutron the mass increases If there is an additional neutron the mass increases Also, they have properties different from other isotopes Also, they have properties different from other isotopes Carbon-14 Carbon-14

9. The Average Atomic Mass The average of the masses of all the isotopes of an atom The average of the masses of all the isotopes of an atom That’s why the average atomic mass is a decimal! That’s why the average atomic mass is a decimal!

10. Average Atomic Mass Tells you the most abundant isotope of an atom. Tells you the most abundant isotope of an atom. Example- Iron (Fe) Example- Iron (Fe) Average atomic Mass: 55.845 Average atomic Mass: 55.845 Round the mass to the nearest whole number Round the mass to the nearest whole number 55.845 round to 56 55.845 round to 56 Iron- 56 is the most abundant isotope of iron Iron- 56 is the most abundant isotope of iron

11. Determine the Most Abundant Isotopes for the Following Elements 1. Lithium (Li) 2. Carbon 3. Oxygen 4. Hydrogen 5. Neon 6. Chlorine Lithium- 7 Carbon- 12 Oxygen- 16 Hydrogen- 1 Neon- 20 Chlorine- 35 and Chlorine- 36