VTT 200 General Sciences Chemistry Gram Formula Weight, Isotopes, Radiation, and Ions

Quick Review… C- H- O- N- P- S- carbon hydrogen oxygen nitrogen phosphorus S- sulphur

Quick Review… Ba- Br- Mg- Fe- Hg- Na- K- Cl- I- Zn- barium bromine magnesium Fe- iron Hg- mercury Na- sodium K- potassium Cl- chloride I- iodine Zn- zinc

Quick Review… Cu- Ni- Se- Co- Si- Au- Ag- copper nickel selenium cobalt Si- silicon Au- gold Ag- silver

Review: Elements & Compounds Element- Only one type of atom involved Molecule-More than one atom Compound- 2 or more ELEMENTS

The Mole—a unit of Chemical measurement—the basics: A mole is the amount of the substance equal in grams to the sum of the atomic weight. Gram Formula Weight- the sum of the atomic masses of all the atoms represented in the formula. Also called the molecular mass

Example… What are the gram formula weights of the following? N2O C6H12O6

Calculate the Gram Formula Weight for the Following… KClO3 Ca(NO3)2 4H2O

Isotopes, Radiation & Ions

Isotopes How did we calculate the number of neutrons in an atom’s nucleus? An Isotope is an Atom of the same element having a different THAN NORMAL number of neutrons.

Isotopes Normal carbon has how many protons? Carbon’s atomic weight is what? So how many neutrons in normal C? In Carbon-14, the atomic weight is 14… This carbon still has the same # of protons or it would not be carbon… But the number of neutrons has changed…Carbon-14 is an Isotope of C

Isotopes Isotopes can be stable or unstable. Unstable isotopes are radioactive and undergo a transformation where they are constantly losing particles become more stable. Carbon-14 is used to determine the relative age of articles—this is C-14 dating

Isotopes Just because an element has a number of neutrons not equal to protons—they are not isotopes! Isotopes by definition are elements with a different THAN NORMAL number of neutrons How does this happen? This is the study of radiation

Radiation Radioactivity is defined as the spontaneous disintegration by emissions of sub-atomic particles like protons, neutrons, or electrons. When these sub-atomic particles collide with human or animal tissues, it may cause damage to the tissue.

Alpha Particles—most deadly 4/2 Helium nucleus with 2 protons and 2 neutrons—let’s look at the Helium atom 4- total particles 2- protons and 2-neutrons This is the type of radiation emitted by the sun and as emitted in a nuclear blast EX: Unstable atom with a large nuclei such as thorium-232 emits an alpha particle, then its atomic number decreases by 2 and mass number by 4—when this happens, protons have changed, which means what??

Beta & Gamma Particles —X-Rays Electrons emitted by atomic nuclei. This happens when a neutron decays into a proton by releasing its negative charge Watch the Example using Uranium: Let’s look at the math: If an neutron decays, a proton is created, therefore, the atomic number of the atom is increased by 1. And what does it mean if the proton count changes, increases by 1?? However, the atomic mass stays the same Watch the following example…

Ions A charged particle formed by an atom that has gained or lost one or more of its electrons. An Ion is an element with a different than normal number of electrons Since elements and atoms strive for balance they may gain or lose valence electrons Follow the instructor’s example

Ions—gain or loss of electrons There are two types of ions: Cation- has lost an electron (positively charged) and are usually metallic Anion- has gained an electron (negatively charged) and are usually non-metallic Alkali Metals form ions with a +1; Ex: Na+¹; K+¹ Alkaline earths +2 (Be, Mg, Ca, Sr, Ba) Halogen gases: Cl-¹, Fl-¹ What are the most important cations and anions in an animal’s body?