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67 Cards in this Set
- Front
- Back
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Measured numbers
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numbers obtained by making measurements
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Exact numbers (non-measured numbers)
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1. Numbers obtained by counting
2.Definitions/Equalities which contains 2 units in the same measuring system |
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If a substance's density is less than 1.000 g/mL, it _____ in water.
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Floats
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If a substane's density is more than 1.000 g/mL, it ____ in water.
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sinks
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Specific Gravity
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value that tells how the density of another substance compares to the density of water.
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Chemistry
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the study of matter at the atomic and molecular level.
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Chemists
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study how elements and molecules change as they undergo reactions and break and form bonds.
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Matter
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anything that that has mass and occupies space.
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Pure Substance
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a) matter with a fixed and defined composition.
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Two types of Pure Substances
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Elements & Compounds
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Elements
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contain one type of atom. It cannot be broken into simpler substances. Ex: Na, C, Br, Se
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Compounds
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are made up of two or more elements. The can be broken down into simpler substances through chemical means. The elements in the compound are chemically bonded.
Ex: H2O, CO2 |
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Mixtures
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matter that consists of two or more substances that are physically mixed but not chemically bonded. Can be seperqated by a physical process.
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Two types of Mixtures
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Heterogeneous and Homogeneous
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Homogeneous Mixture
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Is evenly mixed or distibuted, the composition is the same throughout the mixture.
Ex: salt water, milk, |
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Heterogeneous Mixture
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the substances are not evenly distributed throughout the mixture. Seperates over time and may require shaking.
Ex: sand water, italian dressing, pepto bismal |
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Groups (perodic table)
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the columns of the periodic table. Element in the same group have similar characteristics. They reflect the number of electrons in the valence shell of an atom of an element. 1A-8A
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Group 1A
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Alkali Metals
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Group 2A
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Alkaline Earth Metals
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Group 7A
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Halogens
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Group 8A
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Noble Gases
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Periods (peroidic table)
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Rows of the periodic table. From left to right, the elements are arranged in order of increasing mass. The peroid # signifies the number of shells in the atom of an element.
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The Atom
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The smallest particle of an element that still has properties of that element. Made up of Protons(atomic mass) Neutrons (mass number - atomic number) and electrons(lightest sub-particle of the atom)
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John Dalton's Atomic Theory
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1) All matter is made up of tiny particles called atoms.
2)Atoms of the same element arer similar to each other. 3)Atoms of different elements can combined to form compounds. 4)In chemical reactions atoms are never created or destroyed. |
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Nucleus
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the core of an atom (the majority of an atoms mass is found in the nucleus.
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Electron cloud
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Made of layers (or shells) of electrons, like an onion.
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Subatomic Particles
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Proton(+1)
Neutron(0) Electron(-1) |
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Atomic Number
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Number protons of the element symbol on periodic table. Equal to the number of protons in the element. Also equal to the # of electrons in the atom. Considered to be the identity of an atom.
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Mass Number
(not found on the periiodic table) |
Equal to the #protons + #neutrons in the atom.
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Isotopes
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atoms of the same elements that have different amounts of neutrons.. # of neutrons does not effect identity of an element. # protons does effect the identity of and element. Isotopes are naturally occurring.
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Atomic mass
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a)Below the element symbol on the periodic table; decimal #
b)the average weight(mass) of an element. Weighted average of isotopes(mass number) of an element. |
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Valence electrons
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the electrons in the outer shell(valence shell) of the atom. They are the most important electrons in the atom. The number of valence electrons determine the chemical reactivity. They are the electrons used to bond with other atoms.
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Electron Dot Symbols
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used to represent only the valence electrons of an atom. Element symbol with up to 8 electrons around it. Up to 2 electrons per side.
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Radiation
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Energy in the form of waves or moving subatomic particles. They can be either ionizing or non-ionizing.
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Radiation can either be
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ionizing or non-ionizing
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Ionizing Radiation
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has enough energy to remove an electron from an atom or molecule; all radiation with more energy than visible light is ionizing.
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Atom or molecules loses a electron and becomes a free radical when?
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it is struck by ionizing radiation
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Atoms and molecules that lose an electron steal one from another molecule causing a?
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Free radical chain reaction (if the surrounding molecules happened to be biological molecules, such as DNA or proteins, the damage from free radicals can result in aging, breakdown of tissue, or cancer) affects tissue that replicate frequently such as skin cells, reproduction organs, intestinal lining
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Antioxidants
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are chemical substance that stop free radicals chain reactions. They assist the body's repair mechanism to limit free radical damage.
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Nuclear Radiation
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The energy and subatomic particles emmited by an atom has an unstable nucleus. Comes from the nucleus of the atom.
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Radioactive Decay
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the term given to the emission of radiation by unstable nuclei
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Unstable nucleus
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nucleaus us shifting and constantly rearranging itself. In the process it kicks out Extra energy, Extra subatomic particles *that it does not need*
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Alpha Particles
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-lowest energy
-consists of 2 p and 2 e- -penetrates our skin 2 skin cells deep -causes most damage when inhaled in digestion -protection: skin Ex:Smoke Detectors(americium) US Radium Alexander Litvinenko(Polonium-210, alpha particle emmiter) |
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Beta Particles
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-more energy than alpha
-consists of: one e- -penetrates skin: 5 mm -protection: heavy clothing; lab coat, and gloves -used in cancer radiation therapy |
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Gamma Ray
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-Highest energy nucleur radiation
-consists of: pure energy/no particles -amount of energy similar to X-rays -penetrates skin: >50cm protection: lead, concrete -used in cancer radiation therapy Ex: US Radium, uranium, atomic bombs (emmits both alpha particles and gamma particles) |
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"half Life"
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radioactive isotope shelf life. the amount of the time it takes for 1/2 of a radioactive sample to stop admitting radiation.
a)range from seconds to thousand of years b)radioisotopes chosen for medical applications have short half-lives |
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Octet Rule
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the tendency for atoms to acquire a full valence shell. 8 valence e-. This is why atoms for bonds.
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Reactive and Unstable
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atoms that do not have a full octet....
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Stable and Unreactive
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atoms that have a full octet
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Ionizing (loses or gains electrons)or Sharing
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atom can adjust its electrons to obtain a full octet by:
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Ionic Compound
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-metal and non-metal
-electrons are transferred Ex: NaCl |
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Covalent Compound
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-non-metal and metalloids
-electrons are shared |
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Ion
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-an atom of group of atoms that carry an electrical charge
-the # of protons is not equal the # electons -form when an atom loses or gains electrons |
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Two types of Ions
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cation and anion
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cation ion
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-ion carries a positive + charge
-forms when a metal ion loses its valence electrons -forms from a atom whose valence shell is less than half full |
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anion ion
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-ion that carries a negative - charge
-forms when a metal atom gains valence electrons -form from atom whose valence shell is more than half-full |
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Group 1A and 2A (excludes H in 1A)
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Ionic charge=Group #
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Group 3A
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Ionic charge 3+
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Group 5A-7A
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Ionic charge=
5A -3 6A -2 7A -1 |
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Groups 4A and 8A
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do not ionize
1. Group 4A elements have 4 electrons. a)valence shell is half full b)requires to much eneregy to gain or lose the 4 electrons 2.Group 8A- nobel gases have all eight electron (stable and non-reactive) |
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metal ions (Groups 1A, 2A, 3A)
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when they ionize they will have the same # of electrons as the noble gas above at the end
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nonmetal ions (Group 5A, 6A, 7A)
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when they ionize they will have the same # of electrons as the noble gas at the end of the table
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Properties of Ionic Compounds
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a)crystal and solids
b)hard and brittle substances c)high melting points d)conduct electricity when dissolved in water |
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Metal ionic name
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same as element name
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nonmetal ionic name
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change the ending on the element name to ide
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Polyatomic Ions
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-Group of atoms that carry ionic charges
-stay together when dissolved in water -ammonia is the only one that has a positive charge |
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Polyatomic Ion naming
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name of metal plus name of polyatomic ion.
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