BIOL 111 Chapter Notes - Chapter 2: Ionic Bonding, Electronegativity, Chemical Polarity
Document Summary
Matter- anything that has space and has mass, solid, liquid, gas, etc. Element- substance that can"t be broken down into other substances by chemical reactions ( ag, bi) Compound- contains two or more elements in a fixed ratio ( nacl, caco3) Essential elements- absolutely necessary for an organism to live a healthy life. Oxygen, carbon, hydrogen, and nitrogen make up 96% of living matter. Trace elements ( sulfur, calcium, phosphorous, potassium) account for the other 4%, some required by all forms of life (iron), but others are required for certain species; ex. iodine is required by humans in small quantities. Protons and neutrons are held together tightly in the atomic core, electrons form a cloud of negative charge around the atomic core. Atomic particles are really small to measure, dalton (amu) is used to measure atoms and molecules. Mass number/atomic mass- sum of protons + neutrons in an atom. Atomic number- number of protons in an element.
