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Science Chapter 4 Quiz
Vocabulary
51
Science
8th Grade
10/20/2010

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Term
Atom
Definition
The smallest particle of an element
Term
Electron
Definition
A negatively charged subatomic particle with 1/1836 amu
Term
Dalton's Atomic Theory
Definition
All elements are composed of atoms that can't be divided. Atoms are like smooth, hard balls
Term
Thomson's Model
Definition
Atoms have negatively charged electrons embedded in a positive sphere. It is also known as the raisin muffin model. The raisins are the electrons while the rest are part of a positive sphere.
Term
Rutherford's Model
Definition
An atom was mostly empty space. There is a nucleus in the middle of the atom.
Term
Nucleus
Definition
A tiny region in the center of an atom
Term
Proton
Definition
A positively charged subatomic particle with 1 amu
Term
Bohr's Model
Definition
Electrons move in specific orbits around the nucleus. The model resembles one of a solar system.
Term
Cloud Model
Definition
Instead of electrons moving in orbits like planets, electrons can be anywhere in the cloud-like region around the nucleus.
Term
Energy level
Definition
the specific amount of energy an electron has
Term
Neutron
Definition
A subatomic particle with 1 amu and no charge
Term
Symbols for proton, neutron, and electron
Definition
p+, n, e-
Term
Atomic number
Definition
The number of protons in the nucleus of an atom
Term
Isotope
Definition
An atom of the same element but has a different number of neutrons
Term
Mass number
Definition
The sum of the protons and neutrons in the nucleus of an atom
Term
Atomic mass
Definition
The average mass of all the isotopes of an element
Term
Periodic table
Definition
An arrangement of elements showing the repeating pattern of their properties
Term
Period
Definition
A horizontal row in the periodic table
Term
Group
Definition
A vertical column in the periodic table
Term
Chemical symbol
Definition
An one-letter or two-letter representation of an element
Term
Element
Definition
A pure substance that cannot be broken down into other substances by chemical or physical means
Term
Metal
Definition
An element that is a good conductor of electric current and heat
Term
Malleable
Definition
Able to be hammered or rolled into flat sheets or other shapes
Term
Ductile
Definition
Able to be pulled out or drawn into a long wire
Term
Thermal conductivity
Definition
The ability of an object to transfer heat
Term
Electrical conductivity
Definition
The ability of an object to transfer electric current
Term
Reactivity
Definition
The ease and speed with which a substance reacts with other substances
Term
Corrosion
Definition
The gradual wearing away of a metal due to a chemical reaction
Term
Does the reactivity of metals increase or decrease as you move from left to right across the periodic table?
Definition
Decrease
Term
Alkali metals
Definition
Metals in Group 1 from lithium to francium
Term
Alkaline earth metals
Definition
Metals in Group 2 from beryllium to radium
Term
Transition metals
Definition
Elements in Groups 3 through 12
Term
Lanthanides and Actinides
Definition
Two rows of elements placed below the main part of the period table. The lanthanides are above the actinides
Term
Synthetic elements
Definition
Elements with atomic numbers higher than 92; they are not found on Earth
Term
Particle accelerator
Definition
Powerful machines that make atomic nuclei crash at high speeds; sometimes, they combine into a single nucleus
Term
Nonmetal
Definition
An element that lacks most of the properties of a metal
Term
Carbon Family
Definition
Group 14 Elements
Term
Nitrogen Family
Definition
Group 15 Elements
Term
Diatomic molecule
Definition
A molecule that consists of 2 atoms
Term
Oxygen Family
Definition
Group 16 elements
Term
Halogens
Definition
Group 17 elements
Term
Inert/Noble Gases
Definition
Group 18 elements; very stable
Term
Semimetals
Definition
Elements that have properties of metals but also have properties that are typical or nonmetals
Term
Semiconductor
Definition
A substance that can conduct electric current under some conditions but not under other conditions
Term
Radioactive decay
Definition
A process where the atomic nuclei of unstable isotopes release fast-moving particles and energy
Term
Radioactivity
Definition
A property of being able to spontaneously emit radiation
Term
Alpha particle
Definition
2 protons and 2 neutrons; positively charged; same as a helium nucleus; decreases atomic number by 2 and mass number by 4
Term
Beta particle
Definition
a fast moving electron given off by a nucleus during radioactive decay
Term
Beta decay
Definition
A neutron inside the nucleus changes into a negatively charged beta particle and a proton. The nucleus now has 1 less neutron and 1 more proton; Mass number remains the same but the atomic number increases by 1
Term
Gamma radiation
Definition
Radiation consisting of high-energy waves, similar to X-rays; have no charge and don't cause a change in atomic mass or number
Term
Tracer
Definition
Radioactive isotopes that can be followed through the steps of a chemical reaction or an industrial process
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