Trimester Two Study Guide Period 3 Science

Transcription

1 Trimester Two Study Guide Period 3 Science Important vocabulary: * Free fall: when gravity is the only force acting upon an object * Air resistance: objects flying through air experience this type of fluid friction * Weight: the force of gravity acting upon an object or person at the surface of a planet * Inertia: the tendency of an object to resist an adjustment in motion * Mass: the amount of matter in an object * Force: a push or a pull * Acceleration: A rate at which velocity changes; also net force/mass * Motion: a change in distance * Velocity: speed in a certain direction * Speed = distance A change in distance in a given amount of time Time * Friction: the force between two surfaces when they are rubbing together * Ductile: can be fashioned into a wire * Malleable: easily bends and can be reformed buy hammering * Valence electrons: electrons that are found furthest away from the nucleus, have the highest energy level, they are held loosely and are used for bonding. * Projectile: when an object is thrown * Reference point: a place or object used to compare and determine if something is moving. * Nuclear Fusion: a process in which two atomic nuclei combine forming a larger nucleus (larger element) and releasing huge amounts of energy

2 Important concepts: * Know the relationships between Atomic number, Mass Number, Number of Protons, Neutrons and Electrons Atomic mass: the average mass of all the isotopes of an element Mass number: the sum of protons and neutrons in the nucleus of an atom Number of protons: the same as the atomic number Neutrons: located in the nucleus and has a no charge Electrons: located in the electron cloud and has a negative charge All of these are on the element in a periodic table * Label each part of the following picture and explain what each part represents. 8 is the Atomic Number=number of protons O is the Element Symbol Oxygen is the Element Name is the Atomic Mass * List the physical and chemical properties of metals, nonmetals, and metalloids. Nonmetals : opposite properties of metals, not shiny, poor conductors, mostly gases, solids are brittle Metalloids : in between metals and nonmetals, solids (at room temperature), brittle and hard, semi conductors Metals : shiny, good conductors, maleable, ductile, strong solids, corrosive/rust, solids at room temperature

3 * Describe how new elements are created in stars. Elements are created in stars by the stars squeezing elements inside of their cores. Two or more nuclei collide at high speeds and join to form a new element. This is called nuclear fusion. * How is the periodic table organized? Go into depth, especially about the different groups and their reactivity/properties (Where are metals/nonmetals/transition metals/noble gases located? which are most reactive? Least reactive) The periodic table is organized by the increasing value in atomic number (increasing number of protons),group 1 is on the left, and group 8 is on the right. Metals are on the left, nonmetals are on the right. Transition metals are in the center, and contain familiar elements such as gold, silver and aluminum. The elements in group 1 and 7 are the most reactive. The Noble gases, in group 8 (far right), are the least reactive. * What are the parts of an atom? Describe their location and charge. Neutrons have a neutral charge and are in the nucleus. Protons have a positive and are in the nucleus. Electrons have a negative negative charge and are in the electron cloud.

4 * Describe how radioactive decay works. What is given off? Radioactive decay is when an unstable nucleus gives off radioactive particles and energy call beta particles, alpha particles, and gamma rays. * Write the chemical formula for water and describe the parts. H2O formula H: Hydrogen O: oxygen There are 2 hydrogen atoms for every oxygen atom * Understand the concepts of changes in state of matter (solid/liquid/gas, melting point/boiling point/sublimation/condensation) Solid to liquid melting. requires heat/energy input Liquid gas evaporation (heat/energy input) Solid gas sublimation (heat/energy input) Gas liquid Condensation (heat output/ less energy) Liquid solid freezing Freezing point/temp = melting point/temp boiling point = condensation point/temp * Explain the Law of Conservation of Momentum. Give an example. total momentum of a set of objects stays the same unless outside force acts on it

5 example: when a car hits a cup, if the car moves faster the cup will move farther * Using illustrations, describe the difference between balanced and unbalanced forces. * What does inertia depend on? Inertia depends on mass because the more mass there is, the more inertia there is. Inertia is the resistance to an adjustment in motion, so the more of something there is, the more it is going to resist. An object with more mass will have more inertia than an object with a smaller mass. * What are the two factors that determine the amount of friction that acts on an object? The two factors that determine the amount of friction that acts on an object are the type of surfaces involved and how hard the surfaces push together. * How do you know if an object is in motion? You can tell if an object is in motion by knowing if it has had a change in position with respect to reference point (A place or object used for comparison to determine if an object is in motion)

6 *What are the formulas for acceleration, speed, and momentum? Explain how the variables of each equation affect the answer. Know the units for each. The formulas for acceleration is A = Force/Mass or A = (Final Velocity initial velocity )/ time The units for acceleration is m/s^2 Speed = distance over time. Units: m/s Momentum = mass x velocity units: kg m/s * How does a rocket lift off? Explain in detail, including what force must be great enough to overcome gravity. A rocket takes off by burning fuel. The force of the gas escapes the rocket which provides enough energy to power the rocket up. Then the rocket escapes the force of gravity pulling it back to earth.as long as the thrust, or upward pushing force, is greater than the downward pull of gravity. the rocket accelerates upward into space. This is also known as Newton s 3 Law of Motion. *How do you set up a graph to show the speed of an object? If the slope of the line on your graphs is steep, what does that imply about the motion of the object? To set up a graph to show the speed of an object, you label time on the x axis and distance on the y axis. The steeper the graph, the faster the object is moving. Also be able to answer these four questions in depth. Two of the four will appear on your final. * Compare and contrast ionic and covalent bonds (go into depth!). Give an example of each.

7 Ionic Bonds: Transfer electrons, Strong, between a metal and non metal, high melting pomt, conduct electricity, make crystals (example: salt) Covelant Bonds: Share electrons, make molecules, between non metal and non metal, lower melting point, do not conduct electricity (example: water) * Name the four types of friction and give examples of each. Static Friction: Is the Friction needed to overcome for an object to start moving. It is the strongest type of friction. Example: to make a heavy desk move you must first overcome the force of static friction between the desk and the floor Sliding Friction: Friction between two solids that are sliding against each other. It is weaker than static friction, but stronger than rolling or sliding friction. Example: A kid sliding down a slide. There is sliding friction is between the kid s skin and the slide. Rolling friction: when a object rolls across a surface Example: the force that slows a ball down when a ball rolls on the ground Fluid friction: occurs when an solid object moves through a fluid such as water, oil, or air ( the friction between the water and a surfboard) * What are Newton's three laws of motion? Describe and give an example of each. 1st law : An object at rest tends to stay at rest. An a object in motion tends to stay in motion. Example: clothes on the floor will stay there unless someone moves it. OR when you sit in a moving car and suddenly stop, your body continues to move forward 2nd law: F = ma (or A = F/m) Acceleration of an object depends on the object s mass and net force acting on the object example: If an object gets pushed with more force, then it will move faster 3rd Law: For every action there is an equal and opposite reaction

8 Example: when standing on roller skates, if I push against a wall then the wall pushes back at me with the same force, causing me to move backwards * Compare and contrast speed, velocity, and acceleration. Speed: speed is distance divided by time. It is a measure of how fast something is going. The SI units for speed are meters/sec. Velocity: Velocity is speed in a certain direction. For example; I am traveling 10 m/s North. Acceleration: Acceleration is change in velocity. So if something speeds up, slows down, or changes direction, it has acceleration. The SI units for acceleration are m/sec^2. One can calculate Acceleration knowing the change of velocity of an object in a certain amount of time: The equation is acceleration = (Final velocity Initial Velocity) / Time