Transcript H 2 O
Chapter 2 Questions “Cornell Style” Name Date Period Take notes here Summary – one summary at the end States of Matter Solid -- definite shape & volume (tightly packed) Liquid -- definite volume (not as tightly packed) Gas -- no definite shape or volume (very “loose”) Write a Question now! Element – atoms which all have the same number of protons. 1 type of atom Tom Lehrer’s Element Song http://www.privatehand.com/flash/eleme nts.html Metals – are on the left side Non-Metals – are on the right side 10 Ne 20.18 Atomic number (# of P) Chemical symbol Atomic mass (# P+N) The # of electrons = # of protons Atom – The smallest part of an element that has the properties of that element. “unable to cut” Model of an atom energy levels nucleus [protons (+) & neutrons] electrons (-) Write a Question now! Compounds - two or more elements The kinds of atoms and the proportions of atoms are fixed. Compound or NOT ? Carbon (C) Water (H2O) Salt (NaCl) Sodium (Na) Compound Compound Compound Compound or or or or NOT NOT NOT NOT Number of atoms in a compound. H2O 3 NaCl 2 C6H12O6 24 CH4 5 NH2CH2COOH 10 (NH4)2SO4 15 Write a Question now! Write a 2 sentence summary of these notes. Worksheet -- Element and Their symbols Worksheet -- Number of atoms in a formula Ionic Bonds Formed by a metal and nonmetal. There is an attraction between opposite charges. Examples: Na + + K+ + Cl Br - NaCl KBr Ca 2+ + F- CaF2 “Opposites attract.” Covalent Bonds Formed by two nonmetals. share one or more pairs of electrons Examples: Cl - Cl Cl2 O=O O2 Chemical Reactions – change one set of chemicals into another. Atoms are rearranged--- they are not created or destroyed! Na + + Cl (reactants) 2H2 + O2 NaCl (products) 2H2O Write a Question now! Like all molecules, water is neutral. H H O H2O Polar - an uneven pattern of charge Water is a very good dissolving agent. Hydrogen Bonding water molecules are attracted to each other because of its polar nature cohesion = attraction between similar substances adhesion = attraction between different substances Capillary action = cohesion and adhesion working together Temperature Moderation large water must gain or lose a amount of energy for its temperature to change. Examples: swimming pools ponds lakes ocean This helps animals to maintain a stable temperature (homeostasis) despite outside temperature. Write a Question now! pH scale measures the concentration of hydrogen ions & hydroxide ions (acid) (base) (acid) 0 I I Vinegar I I Stomach acid I (neutral) 7 I I I I I Urine Soap I I (base) 14 I I I Bleach Buffers -- are a weak acid or base that prevents a sudden change in pH Write a Question now!