Science - Exam Preparation PDF

Science - Exam Preparation Density: ​ Mass - The # of particles in a substance ​ Volume - How much space an object takes up ​ V = Length x Weight x Height ​ Physical change - Change to propertie but no new substance ​ Chemical change - Change to properties as a new substance is formed...

Science - Exam Preparation Density: ​ Mass - The # of particles in a substance ​ Volume - How much space an object takes up ​ V = Length x Weight x Height ​ Physical change - Change to propertie but no new substance ​ Chemical change - Change to properties as a new substance is formed 1.​ All matter is made of tiny particles. 2.​ All particles of one substance are the same. Different substances are made of different particles. 3.​ The particles are always moving. The more energy the particles have, the faster they move. 4.​ There are attractive forces between the particles. These forces are stronger when the particles are closer together. Bohr Rutherford Diagrams: ​ Atoms are more stable when their outer shell is completely full or completely empty.  Science - Exam Preparation ​ Sodium is a “metal” because when it reacts it tends to lose electrons. Standard Atomic Notation: ​ Li → Chemical symbol ​ Lithium → Element name ​ Atomic number → Protons (3) ​ Atomic mass → Mass # from periodic table (6.9) ​ Mass number → Atomic mass but rounded (7) ​ Valence electrons → electrons in the outer shell ​ 7 - 3 = 4 → p = 7 | n = 4 Classification of Matter: ​ An alloy is a solution composed of two or more metals. ​ The particle theory of matter describes the composition and behavior of matter. ​ A pure substance is made up of only one type of particle. ​ A mixture is made up of at least two different types of particles. ​ A mechanical mixture contains more than one type of particle, and the different types of particles are visible. ​ A solution contains more than one type of particle but the different types of particles cannot be distinguished visually.  Science - Exam Preparation Electrical Nature of Matter: ​ Electrons can change although protons can not change. ​ Protons are big and located in the nucleus of the atom. It requires extreme forces to change/remove protons. ​ Electrons are light and located in orbits outside of the nucleus. Small forces like friction are enough to change the number of electrons. ​ Repel → +,+ or -,- | Attract → +,- Charging by friction: ​ The energy from rubbing two materials together can cause electrons to be lost. Some materials are better at holding electrons than others. Charging by contact: ​ You need a charged object ​ Like charges repel unlike charges attract Charging by induction: ​ When a charged object is brought close to a neutral object, the charges inside of the neutral object can move. Voltage, Current & Resistance: ​ Voltage → V → Volts (V) ​ Current → I → Amperes (A) ​ Resistance → R → Ohms (Ω)  Science - Exam Preparation ​ If the voltage gets bigger, the current also gets bigger. Series & Parallel Circuits: Series ​ Not as bright ​ Turns both on and off together ​ Less power ​ If one bulb burns out, they both turn off Parallel ​ Bulbs will be brighter ​ Predictable voltage ​ Switches can control the light bulbs independently ​ More power ​ More difficult to build Power + Energy: ​ Power → How much a circuit element is “doing” per second ​ Light bulb → How much light ​ Speaker → How loud ​ Motor → How fast ​ Voltage (V) → Energy per charge ​ Current (I) → Charge per second ​ Power (P) → Voltage x Current ​ Units → Watts (W) ​ Energy → The total power accumulated ​ Units → Joules (J)  Science - Exam Preparation Energy in ecosystems: ​ All energy comes from the sun ​ Sun → Producers (Trophic Level 1) → Herbivores (Trophic Level 2) → Carnivores/Omnivores (Trophic Level 3 and above) ​ Bioaccumulation - Animals with long life spans can accumulate toxins, some toxins are broken down and some toxins do not break down. ​ Bioamplification - Moving up trophic levels increases toxins. Animals at the top of the food chain eat many larger animals with more accumulated toxins. Solar System: ​ The sun provides energy necessary for life on Earth and controls the orbits of all celestial objects in the solar system. It also generates heat and light through nuclear fusion (hydrogen into helium). ​ Tides are the rising and falling of the ocean caused by the gravity of the Moon and Sun.  Science - Exam Preparation ​ "Waxing" means growing (light increases) → “Waning" means shrinking (light decreases).