Science End of Year Review 1
1. The Atom 2
2. History of the Atom Dalton's Atomic Model: Atoms are solid, indivisible balls of different masses Thomson's Atomic Model: Saw the atom as a blueberry muffin (muffin dough is positively charged while blueberries are embedded in them that are negatively charged electrons) Rutherford's Atomic Model: A small, dense, nucleus contains the entire positive charge of the atom, while electrons are scattered randomly in a large space around the nucleus. 3
3. Periodic Table 4
3. Periodic Table A row (period) tells us how many shells an element has. A colum (group) tells us how many valence electrons an element has. Metals are to the left of the staircase, non metals to the right and metalloids along the staircase. Group 1: Alkali Metals Group 2: Alkaline Earth Metals Group 7: Halogens Group 8: Noble Gases 5
4. Representing Atoms Lewis Dot Notation: (Only look at valence electrons) Oxygen: Boron: O B Rutherford Bohr Model: Oxygen: 8+ Simplified Atomic Model Carbon: 6 p+ 2 e 4 e 6
5. Ions P. 42-43 An ION is an atom that has become electrically charged by losing or gaining one or more electrons. How do we know whether an atom will gain or lose electrons? They want to become like the noble gases, they want to become stable and have full valence electron shells. Lithium: Ion form: 3 p+ Oxygen: 8 p+ 2 e 1 e 2 e 6 e 3 p+ 8 p+ 2 e 2 e 6 e 7
6. Solutions and Concentration An aqueous solution is a solution with water. (Ex; Water and Salt) 1% = 1 (g or ml) 100 (ml or g) - 1000 ml L x 1000 1 ppm = 1 g = 1 mg 1000L 1 L g L Calculate the concentration (g/l) if 30 g are dissolved in 250 ml of solution. =? g 1000 L Fill in the left side with your values and cross multiply to solve for? What is the PPM concentration if 0.06 g are dissolved in 3000 ml of solution? Analysis of a 25 L sample of well water shows that it contains 6 mg of dissolved arsenic.what is the concentration in ppm of dissolved arsenic? 8
7. Electrolytes Acids: Start with H Ex: HCl H 2 S0 4 Bases: end in OH Ex: NaOH Mg(OH) 2 Salts: Don't start with H, don't end in OH Ex: NaCl AgNO 3 9
7. Electrolytes PH Scale ranges from 0 to 14 If the PH level is less than 7, the solution is acidic If the PH level is 7, the solution is neutral. If the PH level is greater than 7, the solution is basic. 10
8. Energy a. The Law of Conservaon of Energy : Energy cannot be created nor destroyed; it can only be transferred or transformed. b. Energy efficiency: the percent of energy consumed by a machine or system that was transformed into useful energy. Energy efficiency = Amount of useful energy Amount of energy consumed x 100 Example: A fluorescent light bulb uses 100 joules of electrical energy. 25 Joules is light energy, how energy efficient is this light bulb? 11
8. Energy Thermal Energy: Thermal energy is energy from fire, the sun or a heang element. It comes from the random movement of all the microscopic parcles in a substance. As the temperature increases, there are more parcles and increased thermal energy. 12
9. Chemical Changes > Physical Change: does not alter the nature or the characteristics of matter. The atoms and molecules of the substance do not change. examples: chopping wood (you still have pieces of wood, they are just smaller) folding paper (it's still the same piece of paper) > Chemical Change: alters the nature and characteristic properties of matter. The bonds are rearranged and new molecules are formed. examples: baking bread (there was dough before, now it has changed into bread) burning wood (wood has changed into ashes and embers) 13
9. Chemical Changes The Law of Conservaon of Mass (Maer): The mass before a reacon is equal to the mass aer a reacon p.110 The total mass of reactants is always equal to the total mass of products. Before the reaction During After the reaction CH 4 + 2 O 2 CO 2 + 2H 2 O 16 g + 64 g 44 g + 36 g H H C H O H O O O O C O O H H O H H 14
9. Chemical Changes The Law of Conservaon of Mass (Maer): The mass before a reacon is equal to the mass aer a reacon The total mass of reactants is always equal to the total mass of products. p.110 Example: Which of the following examples below can be used to verify the Law of Conservation of Mass? a) 5 g + 11 g > 12 g + 4 g b) 12 g + 8 g > 6 g + 15 g c) 24 g > 11 g + 13 g 15
Balance Equations Fe + O2 > Fe2O3 16
Balance Equations N 2 + H 2 > NH 3 17
10. Types of Chemical Change Acid Base Neutralizaon : a chemical change involving the reacon of an acid with a base, producing a salt and water Oxidaon : a chemical change involving oxygen (or with properes similar to oxygen) Combuson : a form of oxidaon that releases a large amount of energy Cellular Respiraon : a chemical change where glucose and oxygen are used to generate energy, the reacon also produces carbon dioxide and water Photosynthesis: a chemical change that produces glucose and oxygen from solar energy, carbon dioxide and water 18
Sugar + Oxygen > Energy + Carbon Dioxide + Water Photosynthesis Solar energy + Carbon Dioxide + Water > Sugar + Oxygen 19
11. Electricity Negavely Charged Bodies: have more electrons then protons Posively Charged Bodies: have less electrons then protons Remember that the number of protons never changes! Substances can only lose or gain electrons. Conductors allow the free flow of electrical charges Insulators hinder the free flow of electrical charges Opposite charges aract Like charges repel + + + If A is negatively charged, what charge does C have? A B B C If A is positively charged, what charge does D have? A B B C C D 20
11. Electricity Write down what you know about the situation to help you! 21
11. Electricity repel attract attract repel opposites attract like repel 22
Static Electricity Most objects and substances are neutrally charged (same number of protons and electrons) Objects can become posively (+) charged by losing electrons Objects can become negavely ( ) charged by gaining electrons Tendency to gain electrons (acquire a negative charge) Plastic Nickel Paper What charge will each substance acquire when plastic and wool are rubbed together? Plastic Wool Tendency to lose electrons (acquire a positive charge) Silk Wool Glass What about wool and glass? Wool Glass 23
11. Electricity V=RI P=VI E=P t P: electrical power (watts) V: potential difference (volts) R: resistance (ohms) I: electric current intensity (amps) * E: energy consumed (joules) or (kw h) or (w h) t: time difference (seconds) 24
11. Electrical Circuits Series Circuit Parallel Circuit 25
Magnetism Magnets have a north pole and a south pole. Opposite magnetic poles attract each other. Like magnetic poles repel each other. Magnetic Field Magnetic field lines travel from north to south. 26
Magnetism Electromagnetism: all phenomena resulting from the interaction between electricity and magnetism How? Wrap your fingers around the current so that your thumb points in the direction of the electron flow (from negative to positive). The direction of your fingers (from knuckles to fingertips) determines the direction of the magnetic field. 27
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