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Atoms, Elements. Atoms. Contain 3 particles. Electrons. Protons. Neutrons. What are the characteristics of the particles?. The Electron. The Proton. Negative charge. Positive charge. Participates in chemical reactions. Determines element.
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Atoms Contain 3 particles Electrons Protons Neutrons
What are the characteristics of the particles? The Electron The Proton • Negative charge • Positive charge • Participates in chemical reactions • Determines element • Outer shell e- determine chemical behavior The Neutron Nucleus Consists of: • No Charge Neutrons Protons • Determines isotope
Atoms • The number of electrons • Is equal to the number of protons • Electrons in space around the nucleus
What is the atomic number? Number of protons What is the mass number? Number of protons plus neutrons Atomic number 13 Al Symbol 26.9815 Mass number
Carbon Atomic Number? Mass Number? C atom with 6 ____ 6 • ____ protons 12 6 • ____ neutrons ____
Atomic Number? ____ 2 Helium Mass Number? ____ 4 2 He 4 Protons? ____ 2 Neutrons? ____ 2
Biologically Important Elements Carbon (C) Hydrogen (H) Nitrogen (N) Trace elements Calcium (Ca) Phosphorus (P) Potassium (K) Sulfur (S) Sodium (Na) Chlorine (Cl) Magnesium (Mg) Oxygen (O)
Bonds are formed or broken down in chemical reactions • Ionic bonding • Atoms losing or gaining electrons to complete their outer shells
Covalent bonding • Sharing electrons
Covalent bonding • Sharing electrons
Covalent bonds can be: Double Single Triple
Water Our cells are composed of 70% –95% water Water covers 3/4th of the earth
Water Covalent bonding? Hydrogen bonding? How are the hydrogen and oxygen atoms bonded together? The electrons in its covalent bonds are shared unequally Creates POLARITY
Water Covalent bonding? Hydrogen bonding? How are water molecules bonded together? The polarity of water results in weak electrical attractions between neighboring water molecules Creates HYDROGEN bonding
An acid What is: • A chemical compound that donates H+ ions to solutions? • A compound that accepts H+ ions and removes them from solution? A base • A measure of H+ ion concentration in a solution? A pH scale
Basic A pH Scale Neutral pH 7 [H+] = [OH+] • Biological range maintained at ~ 6.5 – 7.5 • Blood ~ 7.2 – 7.4 Acidic