Chapter 2 Chemistry

Chapter 2 Chemistry - Chapter 2 Chemistry 2.1 Everything is...

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Chapter 2 Chemistry 2.1 Everything is made of atoms - The chemistry that is most important in biology revolves around a few important elements - Element : A substance that CANNOT be broken down chemically into any other substances (Gold, Carbon, Aluminum) - Individual component pieces of an element are called atoms - Atom : A bit of matter that CANNOT be subdivided any further without losing its essential properties - Greek for “indivisible” - EVERYTHING around us can be reduced to atoms -ALL atoms have the same BASIC structure Nucleus : Located at the center of the atoms which is made up of TWO types of particles, called protons and neutrons Protons : Particles that have a positive electrical charge Neutrons : Particles that have no electrical charge Mass : The amount of matter in a proton or neutron Electrons : A negatively charged particles that whirls in a cloud around the nucleus, weighs almost nothing (less than 1/20 th of one 1% of the weight of a proton) Atomic Mass : The COMBINED mass of all of its protons and neutrons - Particles with the SAME change repel around each other; those with OPPOSITE charges are attracted to each other -Electrons… 1. Repel each other 2. Attracted to positively charged protons -Atoms are TINY - Most of the space take up by an atom is EMPTY - The nucleus is very SMALL and COMPACT, the electrons ZIP farm from the nucleus - Atoms have different numbers of protons in the nucleus - Each element is given a name, and an atomic number - Atomic Number : Corresponds to how any protons an element has - 90 elements have been discovered, and 25 can be made in the laboratory - Only 25 elements are found in a human body - 4 elements make up 96% of the body
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- The “BIG 4” are oxygen (65%), carbon (18.5%), hydrogen (9.5), and nitrogen (3%) - The number of protons determines what element it is - The number of neutrons is equal to the number of protons - The mass of the atom doubles the atomic number 2.2 An atom’s electrons determine how (and whether) the atom will bond with other atoms - An atom’s electrons determines how (and whether) it will bond with other atoms - Electrons move quickly, but stay within their prescribed area, called an Electron Shell - 1 st electron shell closest to the nucleus can hold TWO electrons - 2 nd electron shell can hold as many as EIGHT electrons - Atoms become stable when their outermost shell is filled to capacity - Atoms that have outer shells with vacancies are likely to interact with other atoms - Based on the number of electron vacancies predicts how amenable to bonding that atom will be - Atoms have the same number of electrons and protons - An atom with extra electron becomes negatively charged - An atoms lacking or more electrons is positively charged - Ion : An atom that carries an electrical charge, positive or negative, because it has either gained or lost an electron or electrons from its normal, stable configuration - Ions are like to interact with oppositely charged ions 2.3 Atoms can bond together to form molecules or compounds - Molecules : Groups of atoms held together by bonds
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