Science Exam Notes
Electrostatic Precipitators- a device to control air pollution using stationary electric charges (static electricity). They can remove 99.99% of the solids and liquids from gases. Rutherford Theory- the centre of the atom has a positive charge. The centre is called the nucleus. It contains most of the atoms mass, but occupies a very small space. The nucleus is what made some particles bounce back during the experiment. The nucleus is surrounded by a cloud of negatively charged electrons. Most of the atom is empty space. Bohr Theory- Electrons orbit this nucleus of the atom much like the planets orbit the sun. Each electron in an orbit had a definite amount of energy. Electrons cannot be between orbits, but they can jump to and from different orbits. Each orbit can hold a certain maximum number of electrons. The maximum number of electrons in the first, second, and third orbits is 2,8 and 8 respectively. Alkali Metals- Lithium (Li), Sodium (Na) Alkaline Earth Metals- Magnesium (Mg), Calcium (Ca) Halogens- Fluorine (F), Chlorine (Cl) Physical Properties- Luster,state,crystal form, malleability, ductility, hardness, scratched or dented, optical clarity. Melting and Boiling Point- Temperature at which substances change state (e.g. water changes from ice to liquid at 0 degrees celsius and from liquid to vapor at 100 degrees. Conductivity- Ability to transmit electricity and heat. Viscosity- How easily a liquid flows (e.g. syrup is more viscous than water.) Solubility- The ability of a substance to dissolve in a solvent. Density- The amount of matter per unit volume (e.g. the density of water is 1.0g/cm3) Qualitative Properties- are descriptive in nature. Quantitative Properties- are measured therefore require a number. Change Of State- Most kinds of matter can change from one state to another. Example:Water (H2O) Liquid water can freeze at 0 degrees and turn into a solid (ice.)
Science Exam Notes
Comparison of periods and groups on periodic tableperiods(rows)-all elements have the same number of atomic orbitals groups(columns)-all elements have the same number of electrons in outer orbitals Bioaccumulation- The concentration of a substance within a species and the species affected the most is the initial species to inject the substance. Autotrophs- An organism capable of synthesizing its own food from inorganic substances, using light chemical light or chemical energy. Green plants,algae, and certain bacteria are autotrophs. Heterotrophs- An organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition. Artificial Ecosystems- man-made, human managed, look remains the same, plants selected by humans. Natural Ecosystems- living organisms interact freely, not maintained or planned by humans, changes occur as one planter animal gradually replaced another. Resistance- the force that stops or slows the electrical charge. Pure Substances-a substance made up of only one type of particle.(e.g. elements, compounds.) Elements- pure substances that cannot be broken down into simpler substances Compounds- pure substances that have two or more different element in a fixed proportion. These substances cannot easily be separated into their elements without the input of a lot of energy. Mixtures- A substance made up of at least two different types of particles. (e.g.homogeneous solutions, heterogeneous mechanical mixture.) Homogeneous Solutions- A uniform mixture of two or more substances. Mixtures can be solids,liquids,gases or a mixture of these particles. Alloys- a solution of two or more metals Heterogeneous Mechanical Mixtures- A mixture in which you can distinguish different types of matter. Solar System- The sun together with the eight planets and all other celestial bodies that orbit the sun
Science Exam Notes
Galaxy- A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction. Color of a star indicates color, temperature, and age.
