Half Life

Half life is defined as the time it takes for a half of the sample to decay into a stable form. For example, if you start off with 100 grams of a sample, and the half life is two days, in two days you will have 50 grams, the next two you will have 25, and so on.
            We did a lab on half life, we had to figure out who the missing person was by figuring out how long they have been dead. For this experiment, we cut up little pieces of paper and then dumped them out from a cup. The one facing up we took out, they demonstrated the atoms that have been decayed in the first half life. Each half life took ten years; we repeated this six more times. With this information, we found out who was missing.

Radioactive Decay

There are three kinds of radioactive decay, Alpha decay, Beta decay, and Gamma decay. Alpha decay always has a helium nucleus, it has a mas number of four and an atomic mass of negative two. Beta decay is when a neutron changes into a proton, its mass number remains unchanged and its atomic number adds one. Gamma decay has no change in both its mass number and atomic number. It always accompanies alpha and beta decay. So even when a decay formula doesn't have gamma listed, we know it's there, it's just not implied.

Mass of Subatomic Particles

Today in class I learned about the mass of subatomic particles. Protons contain 1 amu, neutrons contain 1 amu, and electrons contain 1/1840 amu( amu stands for atomic mass unit). Protons are a part of the atom that gives an element its identity and mass. Electrons gives it reactivity, and neutrons give an element mass and isotope determination. Isotopes have the same number of protons but a different number of neutrons, and has different atomic masses even though it is the same element. When doing isotomic symbols, the mass number (A) is on top, atomic number (Z) is on bottom and the element symbol (X) is to the right of these number. This is what it looks like ( but its suppose to be centered).
AX 
Z

Different Scientist

We talked about different scientist and their views and theories on chemistry. JJ Thomson used a cathode ray tube to show the atoms of any element emit particles with a negative charge. Think about the chocolate chip cookie model! Rutherford's Gold foil experiment gave us protons, and proved presence of positive charge center in an atom. The current atomic model is a cloud model displaying electron location pinpointed using probability.