1. Therefore: There are 3 subatomic particles: protons, neutrons and electrons. These are measured in “ atomic mass units ” ( amu ) as their mass is so small. Subatomic Particle Mass (amu)LocationCharge Proton ( p + ) 1.673 x 10 -27 kg (1.0073 amu or 1 amu ) Neutron ( n 0 ) 1.675 x 10 -27 kg (1.0087 amu or 1 amu ) Electron ( e - ) 9.1x 10 -31 kg (0.0005 amu or 0 amu )

2. Atomic Number and Mass Number Atomic Number = the number of protons – Unique to each element – In a neutral atom, the number of protons equal the number of electrons. Mass Number equal to the total number of protons + neutrons in the nucleus of an atom. Ex) carbon-12

3. Isotopes Atoms that have the same number of protons but a different number of neutrons ( mass.) Isotopic Notation Shorthand way of representing an isotope of an element. Ex) top number is the mass number (#p + #n) bottom number is the atomic number (#p) May also be written: chlorine-37 or Cl-37 The actual average atomic mass for all chlorine isotopes is 35.45 amu

4. Isotopes of Hydrogen a. hydrogen (hydrogen – 1) 1p + 0n 0 b. deuterium (hydrogen – 2) 1p + 1n 0 c. tritium (hydrogen – 3) 1p + 2n 0 IsotopeProtonsNeutrons Mass Number Electrons Isotopic Notation Carbon-12 66126 Carbon-13 67136 Carbon-14 68146

5. Ions Formed when an atom gains or loses an electron a. Charge = # of protons - # of electrons Ex) Mg +2 = lost 2 electrons # of protons: 12 # of electrons: 10 Charge: +2 Positively Charged ion - CATION Ex) N -3 = gained 3 electrons # of protons: 7 # of electrons: 10 Charge: -3 Negatively Charged ion - ANION

6. CATION “cat”ion ca+ion ANION “ant”ion

7. IsotopeProtonsNeutrons Mass Number Electrons Isotopic Notation Charge Mg-25 12132510+2 N-14771410-3 Br-7935447936

8. Atomic Mass: The mass of an atom expressed in amu (atomic mass units.) One amu is equal to 1/12 the mass of a carbon-12 atom. Average Atomic Mass: The weighted average of all an element’s isotopes. Mass Spectrometers are instruments used to measure masses of isotopes as well as their isotopic abundance. This is the number shown in the box on the Periodic Table. It is calculated by: (mass 1 x % 1 ) + (mass 2 x % 2 ) + …

9. Calculation of atomic mass Magnesium has 3 naturally occurring isotopes: 78.99% Mg-24, 10.00% Mg-25, and 11.01% Mg-26 Calculate the atomic mass of magnesium. (24 x 0.7899) =18.9576 =18.96 + (25 x 0.1000) =2.500= 2.500 + (26 x 0.1101) =2.8626= 2.863 24.323  24.32 amu

10. Calculation of atomic mass Magnesium has 3 naturally occurring isotopes: 78.99% is 23.98504 amu 10.00% is 24.98584 amu 11.01% is 25.98259 amu Calculate the atomic mass of magnesium. (23.98504 amu x 0.7899) + (24.98584 amu x 0.1000) + (25.98259 amu x 0.1101) 24.31 amu

11. The MOLE Atomic Mass - the mass of an atom, based on a C-12 atom, in atomic mass units (amu) 1 amu = 1.66 x 10 -24 g = 1/12 the mass of a C-12 atom Example: atomic mass of Na = 23.0 amu Atoms are too small to count or mass individually. It is easier to count many or mass many. amu gram ( atomic scale) (macroscopic scale) mole

12. mol Mole = amount of substance that contains 6.02 x 10 23 particles (abbreviated: mol) 6.02 x 10 23 particles Avogadro’s Number = number of particles in a mole = 6.02 x 10 23 particles Particles can be atoms, ions, molecules, or formula units Molar Mass = mass, in grams, per 1 mole of a substance units = grams/mole (g/mol) 1 Mole = 6.02x10 23 particles of substance 1 Mole = mass (g) of substance from PT

13. Nuclear Reactions Change the composition of an atom’s nucleus. Protons & neutrons are called nucleons ; atom is called the nuclide.

14. Nuclear vs. Chemical 1.Elements may be converted from one to another 2.Particles within the nucleus are involved. 3.Tremendous amounts of energy are released (million times that of chemical) 4.Rate of reaction is not influenced by external factors. 1.No new elements can be produced 2.Only electrons participate 3.Relatively small amounts of energy are absorbed or released 4.Rate of reaction depends upon factors such as temperature and pressure

15. Nuclear Radiation Penetrating Power Ionizing Radiation is radiation with sufficient energy to change atoms and molecules into ions (can damage living tissue). Nonionizing Radiation is radiation that does not have sufficient energy to ionize matter.

16. Alpha & Beta Decay

17. Types of Spontaneous Radiation : A. Alpha Decay – spontaneous emission of alpha particle from the nucleus; from neutron-poor heavy nuclei B. Beta Decay – spontaneous emission of beta particle from the nucleus; from neutron-rich nuclei

18. Characteristics of Subatomic Particles and Rays: 1 amu = 1.6605x10 -27 kg ParticleMass (amu)ChargeSymbolStopped by Proton ( Hydrogen nucleus ) 1.00727647 Neutron 1.00866490 Beta Particle (electron) 0.0005486 Alpha Particle (Helium nucleus) 4.00150617 Gamma Ray (high energy EMR) 0 Positron (positively charged electron) 0.0005486 0 0

19. Nuclear Bombardment Reactions target nucleus projectile new isotope (element) ejected particle Unstable compound nucleus

20. Nuclear Bombardment Reaction

21. Radioactive Decay of Strontium-90 What is the ½ Life of Strontium-90??? How long until no more Strontium-90 remains?

22. What is the Half-Life of this Radioactive Sample?