BIOL 021 Lecture Notes - Lecture 2: Atomic Number, Ct Scan, Chemical Bond
Document Summary
Everything in the natural world is governed by the laws of chemistry. We use chemistry without thinking about it (cooking, cleaning) All substances in the world are called matter. Matter is anything that has mass and occupies space. Can exist as: a solid, gas, liquid or plasma. An element is pure matter that cannot be broken down into a simpler form. Almost 100 naturally occurring elements (gold, silver, carbon, oxygen, nitrogen, sodium) All elements are made up of tiny particles called atoms. Smallest basic unit of an element that still has its chemical and physical properties. Electrons orbit around the nucleus - negatively charged. Attracted to the charge of the nucleus like a magnet. # of electrons = # of protons in a neutral (uncharged atom) The electrons in the valence shell determine atom reactivity. How we organize our elements according to atomic number at the top (number of protons in the nucleus)
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