Subatomic Particles and Isotopes Subatomic Particles n Protons

Subatomic Particles and Isotopes

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

Electrons n n n 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 n n In a neutral atom, # protons= #electrons If electrons ≠ protons, the atom has a charge n n Known as an ion If more protons- atom has a positive charge If more electrons- atom has a negative charge To find the charge: n charge= protons - electrons

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

Isotopes n n n #protons ≠ #neutrons Mass number= #protons + #neutrons What is the mass number of carbon with 8 neutrons? n Answer: 14 n 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? n They contribute to the mass of the atom. n Why? Most of the mass of the atom is from protons and neutrons n If there is an additional neutron the mass increases n n Also, they have properties different from other isotopes n Carbon-14

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

Average Atomic Mass n n Tells you the most abundant isotope of an atom. Example- Iron (Fe) Average atomic Mass: 55. 845 n Round the mass to the nearest whole number n n n 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 Chlorine 36