Chapter Two

Key Terms:
Matter: Anything that has mass and occupies space.
Element: A substance that cannot be broken down to other substances by ordinary chemical means.
Trace Elements: Needed by all forms of life but in very few amounts.
Compound: a substance consisting of two or more different elements combined in a fixed ratio.
Atom: Smallest form of matter.
Proton: subatomic particle with a single positive electrical charge.
Electron: subatomic particle with a single negative electrical charge.
Neutron: electrically neutral. (no electrical charge)
Atomic Number: same unique number of protons
Mass Number: Sum of the protons and neutrons in the nucleus.
Atomic Mass: Approximaely equal to its mass number.
Isotope: an element that has the same numbers of protons and electrons and behave identically in chemical reactions, but have different number of neutrons.
Radioactive Isotope: one in whicht he nucleus decays spontaneously, giving off particles and energy.

Reading Journal:
1) What is Matter and what does it consist of? Matter is anything and everything that occupies space. Even a small atom is considered matter. All living organisms are compose of matter.
2) What is Polarity? It is when electrons are not shared equally due to differences in electronegativity. For example, water is H2O. if there were a diagram, there would be one oxygen atom between two hydrogen atoms. Hydrogen has a postive charge and oxygen has a negative charge. Therefore, there is a higher positive charge than a negative charge.
3) What is the PH scale? The PH scale is used to describe how acidic or basic a solution is. PH stands for potential of Hydrogen. The scale ranges from 0 to 14, with 0 being the most acidic and 14 being the most basic. The PH unit stands for a tenfold change in a concentration of hydrogen atoms. On the PH scale, 7 is neutral.

Five Facts:
1) Atoms are the smallest unit of an element. It will usually consist of neutrons, protons, and electrons.
2) Ice is less dense than water. Usually, a solid is more dense than its liquid form. The hydrogen bonds in ice hold molecules in ice further apart than in water.
3) An aqueous solution is one in which water is the solvent.
4) Surface tension is a measure of how difficult it is to stretch or break the surface of a liquid.
5) Electronegativity is when an atom's attraction for shared electrons.

Living organisms are actually composed of abotu 25 elements. Four of them include oxygen, carbon, hydrogen, and nitrogen- which make up about 96% of the human body. An element is asubstance that cannot be broke down to other substances by ordinary chemical means. All living organisms are composed of matter. Matter is anything and everything that occupies space and has mass. Trace elements are also apart of the 25 elements. Even though there are only trace amounts inside the human body, they are essential for the body's health.
A compound is a substance consisting of two or more different elemetns combined in a fixed ratio. Most compounds consist of only two elements. But, most of the compounds in living organisms contain at least three or four elements; mostly hydrogen, carbon, oxygen, and nitrogen. Different arragnements of the atoms of the elements determine unique properties for each compound. An atom is the smallest unit of matter that contains properties of an element. There are three kinds of particles; Protons(+), Electrons(-), and neutrons. Protons are a subatomic particle with a single positive charge. Electrons have a negative charge while neutrons are neutral, or no charge. Isotope is a variant form of an atom. Isotopes of an element have the same number of protons, but different number of neutrons.

Ice is actually less dense than its liquid form, water. On the left is an example of water and the right is ice.







Video Link:
http://www.youtube.com/watch?v=zEX2aGpIDBY