ch5
Terms
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- electrical charge
- an excess or deficit of electrons on an object
- electricity
- a force, more powerful than gravity, that moves objects both toward and away from each other, depending upon the charge
- static electricity
- a phenomenon caused by the transfer of electrical charge between two objects. often observed as lightning or as sparks produced when walking across a wool rug on a dry, cold day. formed with friction. is a force because it moves something
- atom
- fundamental building block for all matter; the smallest representative sample of an element. it consists of a positively charged nucleus surrounded by negatively charged electrons
- electrons
- tiny, negatively charged partials that surround a positively charged nucleus of an atom
- protons
- one of two primary building blocks of the nucleus; with a positive electrical charge of +1 and a mass 1.67 X 10 ^-24 g approximately equal to that of the neutron
- positive electrical charge
- a deficiency of electrons on an object; remove electrons from atom, atoms cannot gain protons
- negative electrical charge
- an excess of electrons on an object; add electrons to atom, atoms cannot loose protons
- ion
- an atom that has an electrical charge, from either the loss or gain of an electron
- anion
- a negatively charged ion
- cation
- a positively charged ion
- Coulomb's Law
- an empirically derived rule that states that the magnitude of the electrostatic force between any two objects is proportional to the charges of the two objects, and inversely proportional to the square of the distance between them; opposite attract same repel
- Coulomb
- the unit for measuring the magnitude of an electrical charge
- Electric Field
- the force that would be exerted on a positive charge at a position near a charged object, every charged object is surrounded by an electric field
- Magnetic field
- a collection of lines that map out the direction that compass needles would point in the vicinity of a magnet. exit from north enter south polr
- magnetic declination
- angle between earth's magnetic North pole and geographic North pole
- magnetic dip
- angle of magnetic lines to the surface of the earth
- dipole
- the magnetic field that arises from the two poles of a magnet
- monopole
- one magnetic pole; a section of a magnet that is just one pole (eigher North OR South)
- electrical current
- a flow of charged particles, measured in amperes must need source of energy, closed path, and load
- battery
- a device that converts stored chemical energy into kinetic energy of charged particles (usually electrons) running through an outside wire
- load
- the location in an electric circuit where the useful work is done, such as the filament in a light-bulb or the heating element of a dryer
- voltage
- the pressure produced by the energy source in an electric circuit, measured in volts
- resistance
- magnitude depends on nature of material (conductor or insulator), length of conductor, cross-section of conductor, and temperature.. higher resistance higher the temp = fire
- ampere
- a unit of measurement for the amount of electrical current (number of charges) flowing in a wire or elsewhere per unit of time
- volt
- measure of electrical pressure
- ohm
- a unit of measurement for the electrical resistance of a wire
- direct current
- a type of electrical current in which the electrons flow in one direction only; example: in the chemical reaction of a battery
- alternating current
- a type of electrical current, commonly used in household appliances and cars, in which charges alternate their direction of motion
- power
- the rate at which electrical energy is used- increases with current and voltage increase
- electromagnetism
- electrical currents produce a magnetic field
- electromagnet
- a device that produces a magnetic field from a moving electrical charge
- electromagnetic induction
- a process by which a changing magnetic field produces an electrical current in a conductor, even though there is no other source of power available
- Maxwell's equations
- 1. like charges repel and unlike charges attract (Coulomb) 2. there are no magnetic monopoles in nature (Gilbert) 3. magnetic phenomena can be produced by electrical effects (Oersted) 4. electrical phenomena can be produced by magnetic effects (Faraday)
- wave
- traveling disturbance; carries energy from place to place without requiring matter to travel cross the intervening distance
- wavelength
- distance between two crests or two trough
- frequency
- number of waves that come by each second measured in cycles/sec Hz higher pitch higher the frequency
- velocity
- speed and direction of the wave crest
- amplitude
- height of wave crest above the rest position higher amplitude higher loudness
- transverse wave
- wave in which motion of the wave is different from the motion of the medium in which the wave moves __---__ ex cork in water
- longitudinal wave
- wave in which motion of the wave is in the same direction as the motion of the medium in which the wave moves --- ex slinky falling down stairs, sound waves
- interference
- 2 waves from 2 different sources come together at the same point. amplitude of the observed wave is the sum of the amplitudes of the interfering waves
- constructive interference
- two waves act together to reinforce or maximize the wave height at the point of intersection (louder)
- destructive interference
- two waves intersect in a way that decreases or cancels out the wave height at the point of intersection (nothing)
- electromagnetic wave
- a form of radiant energy that reacts with matter by being transmitted, absorbed, or scatters. no medium required travels really fast constant speed
- doppler effect
- change in frequency or wavelength of a wave detected by an observer because the source of the wave is moving
- transmission
- light passes through the material with no absorption by the material
- refraction
- response of an electromagnetic wave to matter, in which the wave slows down and alters direction
- absorption
- when light is absorbed the material soaks up the wave and its energy converts to another for ex heat
- scattering
- rapid absorption and re-emission of the wave
- diffuse scattering
- light waves are absorbed and re emitted in all directions by a medium such as clouds or snow wood
- reflection
- light waves are scattered at the same angle as the original wave mirror glass
- electromagnetic spectrum
- entire array of waves, varying in frequency and wavelength; but all resulting from an accelerating electrical charge; shortwave length/high frequency: gamma, xray, ultraviolet, infrared, microwave radio
- element
- material made from a single type of atom, which cannot be broken down any further
- molecule
- a cluster of atoms that bond together; the basic constituent of many different kinds of material
- compound
- composed of more than 1 element
- electron
- anatomic particle with negative charge and low mass
- nucleus
- the small massive central part of an atom
- ion
- an electrically charged atom
- orbit
- ...
- ground state
- the lowest energy level of an atom
- excited state
- all energy levels of an atom above the ground state
- quantum leap
- a process by which an electron changes its energy state without ever possessing an energy intermediate between the original and the final energy state
- spectrum
- the characteristic signal from the total collection of photons emitted by a given atom that can be used to identify the chemical elements in a material; atomic fingerprint
- absorption spectrum
- the characteristic set of dark lines used to identify a chemical element or molecule from the photons absorbed by the material atoms or molecules
- emission spectrum
- the characteristic set of lines used to identify a chemical element or molecule from the total collection of photons emitted during quantum leaps
- periodic table
- lists more than 110 elements by atomic weight (in rows) and chemical properties (in columns). the pattern of elements in the periodic table reflects the arrangement of electrons in their orbit
- noble gas
- elements listed in the far right hand column of the periodic table of elements, including helium, argon and neon, which are odorless, colorless, and slow to react
- electron shell
- a specific energy level in an atom that can be filled with a predetermined number of electrons
- static electricity & magnetism vs gravity
- 1. stronger than gravity 2. both attractive and repulsive.. gravity only attractive opposes gravity
- magnetism
- stronger than gravity, attractive and repulsive, newtons law of motion tells us its a force its moves there is energy
- magnet source
- lodestone- composed mineral called magnetite- attracts iron, steel, cobalt, nickel
- earths magnetic field
- giant magnet through center of earth; north is really the south; magnetic declination
- wave equation
- velocity=wavelength X frequency
- sound waves
- alternating regions of compression and expansion of medium conducting sound. vibration of medium (matter) kinetic energy --> sound energy; need vibrating object and medium (air)
- Aristotle vs Democritus
- matter is continuous vs matter s discrete
- Dalton
- every element there is a unique indivisible object called atom. two or more atoms stick together to form a molecule. chemical reactions are just a reshuffling of atoms from one combination to another
- Dalton Observation
- 1. the existence of elements. chemical substance which could not be broken down into another substance 2. the law of conservation of matter. in a chemical reaction; matter neither created nor destroyed can change one form to another 3. the law of definite proportion. composition of a compound is constant it is fixed
- valence electron
- electrons in outermost level in atom; chemical bonding; column #
- core electron
- electrons in inner shells; not involved in bonding; row #
- filled shell
- 2, 10, 18, or 36 electrons- magic number noble gases
- intramolecular bonds
- atoms joins together to form molecules, electrons rearranged inside; within
- intermolecular bonds
- hold molecules together to form bulk properties, no electron rearrangement; different states of matter; between 2 molecules
- ionic bonds
- chemical bond in which attractive forces between oppositely charged ions hold together; give up and accept ion; positive charge = negative charge Na+ Cl- -> NaCl
- covalent bonds
- chemical bond in which clusters of neighboring ions share electrons; bond between left and right side; strong but brittle complex
- metallic bonds
- electrons in a metal are redistributed so that they are shared by all the atoms; left side only
- polar bonds
- unequal sharing of electrons in the formation of covalent bonds- H+-Cl-
- hydrogen bonds
- dipole-dipole interaction hydrogen atoms is in a covalent bond with O, N, F or Cl
- Van der Waals forces
- hold together non-polar molecules
- states of matter
- solid, liquid, gas, plasma
- gas
- molecules which expand to take shape of and fill the volume; force very weak, movement is rapid, random and independent; large space in between individual particles
- liquid
- molecules with no fixed shape but will retain a definite volume; force is weaker than solid but holds particles together; movement is faster and more random than solid; medium distance between molecules;
- solid
- most structure; materials with fixed shape and volume; strong force; very small distance between particles; no movement except vibration in place
- glass
- random structure; no long range order to their atomic structure
- crystal
- all particles line up in a perfect order; regular repeating sequences of atom; regular faces and angles ex salt, sand, computer chip
- plastic
- synthetic polymers; composed of extremely long and large molecules; formed from numerous smaller molecules joined together like links forming a chain; one dimensional structure with a predictable sequence
- plasma
- metallic bond; collection of gaseous + ions surrounded by a sea of electrons; charged gas, hot temperature; conducts electricity ex stars, neon lights, tv
- polymer
- extremely long and large molecules that are formed from numerous smaller molecules, like links of chains, with predictable repeating sequence of atoms along the chain
- change in state
- heat is needed; due to change in forces between molecules and the distance between them
- melting
- heat needed; liquid and solid
- freezing
- heat needed; liquid and solid
- evaporation
- gas and liquid
- sublimation
- gas and solid
- condensation
- gas and liquid