1. Subatomic Particles

2. 1. Subatomic Particles ParticleSymbol (table O) ChargeMass (amu) Location Electrons e 0 e -1 0 β -1 Negative (-1) 1/1872 amu 0 amu Outside nucleus (energy levels) Protons p 1 p 1 1 H 1 Positive (+1)1 amuNucleus Neutrons n 1 n 0 Neutral (0) 1 amuNucleus

3. Special notes on subatomic particles In a neutral atom # of protons=#of electrons. Atoms are electrically neutral. If the number of protons does not equal the number of electrons you have a charged atom known as an ion. # protons > # electrons forms a + ion (cation) # electrons > # protons forms a – ion (anion) The charge on the nucleus is positive. Most of the mass of an atom is in nucleus.

4. 2.Atomic Number (z) 1913—Henry Mosley Used to identify an atom Indicates the number of protons In a neutral atoms also gives the number of electrons Also called the Nuclear Charge

5. 3. Mass Number (A) Total number of protons and neutrons in the nucleus of an atom. (nucleons) Notation: A X Z Mass # = #protons + # neutrons # neutrons = Mass # - # protons

6. Try the following: Sample AtomNotationProtons (atomic #) Neutrons (mass #- atomic #) Electrons(sa me as atomic#) Carbon-12 C-12 12 C 6 612-6=66 Chlorine-35 Cl-35 35 Cl 17 1735-17=1817 Chlorine-37 Cl-37 37 Cl 17 1737-17=2017 Neon-20 Ne- 20 20 Ne 10 1020-10=1010 Oxygen-16 O- 16

7. Determine the # of protons, neutrons, and electrons for these added examples: 19 F 9 9 protons 19-9=10 neutrons 9 electrons 19 F 9 -1 9 protons 10 neutrons 10 electrons 24 Mg 12 12 protons 24-12=12 neutrons 12 electrons 24 Mg 12 +2 12 protons 12 neutrons 10 electrons

8. 4.Isotopes Thomson (1912) found 2 types of neon atoms and Soddy (1910) found 2 types of uranium atoms. 2 elements that have the same atomic number but different mass numbers Based on atomic structure: 2 elements that have the same number of protons but different number of neutrons. For example: Cl-35 and Cl-37

9. 5. Atomic Mass Decimal number Average of all the naturally occurring isotopes for a particular element If you round the atomic mass it gives you the mass number for the most common isotope. Unit is amu (atomic mass unit) 1 amu is 1/12 the mass of C-12 Gram atomic mass= amu but in grams

10. Try the following: 1. Determine the number of protons, neutrons, and electrons for the following isotopes of hydrogen: Solution: Hydrogen-1 (protium) 1 H 1 1p,0n,1e Hydrogen-2 (deuterium) 2 H 1 1p,1n,1e Hydrogen-3 (tritium) 3 H 1 1p,2n,1e

11. 2.Naturally occurring chlorine consists of 75% Cl-35 and 25% Cl-37. Find the average atomic mass..75(35) +.25(37)= 35.50 amu or 75(35) + 25(37) =35.50 amu 100

12. 3. Calculate the atomic mass of an element with isotope A occurring 70.0% of the time with a mass of 13.0 amu and isotope B occurring 30.0% of the time with a mass of 15.0 amu..70 (13.0) +.30 (15.0) =13.6 amu

13. 4.An element X has three isotopes X-30 has a 50.0% abundance, X-28 has a 30.0% abundance and X-31 has a 20.0% abundance..500(30) +.300(28) +.200 (31) = 29.6 amu

14. 5. There are two isotopes of element Z, 60.0% of the atoms have a mass of 58.0 amu and 40.0% have a mass of 57.0 amu. Calculate theatomic mass of element Z..600(58.0) +.400(57) = 57.6 amu