Subatomic Particles

1. Subatomic Particles Particle Symbol (table O) Charge Mass (amu) Location Electrons e 0e-1 0β-1 Negative (-1) 1/1872 amu 0 amu Outside nucleus (energy levels) Protons p 1p1 1H1 Positive (+1) 1 amu Nucleus Neutrons n 1n0 Neutral (0)

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.

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

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

Try the following: Sample Atom Notation Protons (atomic #) Neutrons (mass #-atomic #) Electrons(same as atomic#) Carbon-12 C-12 12C6 6 12-6=6 Chlorine-35 Cl-35 35Cl17 17 35-17=18 Chlorine-37 Cl-37 37Cl17 37-17=20 Neon-20 Ne-20 20Ne10 10 20-10=10 Oxygen-16 O-16

Determine the # of protons, neutrons, and electrons for these added examples: 24Mg12 12 protons 24-12=12 neutrons 12 electrons 24Mg12+2 12 neutrons 10 electrons

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

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

Try the following: Determine the number of protons, neutrons, and electrons for the following isotopes of hydrogen: Solution: Hydrogen-1 (protium) 1H1 1p,0n,1e Hydrogen-2 (deuterium) 2H1 1p,1n,1e Hydrogen-3 (tritium) 3H1 1p,2n,1e

Naturally occurring chlorine consists of 75% Cl-35 and 25% Cl-37 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

3. Calculate the atomic mass of an element with isotope A occurring 70 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

An element X has three isotopes X-30 has a 50 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

5. There are two isotopes of element Z, 60 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