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41 Cards in this Set
- Front
- Back
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What is anything that takes up space and has mass?
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Matter.
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What is mass?
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The amount of matter an object has.
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What is weight?
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The pull of gravity on the mass of an object.
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What does matter consist of?
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Chemical elements in pure form and in combinations called compounds.
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What are the simplest substances?
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Elements.
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How many naturally occurring elements are in existence?
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92.
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What is a substance consisting of two or more elements combined in a fixed ratio?
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A compound.
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How many elements do humans need that are essential to life?
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25.
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How many elements do plants need that are essential to life?
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17.
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What 4 elements make up about 96% of all living matter?
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Carbon, Oxygen, Hydrogen, and Nitrogen.
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What are elements that are required in extremely small amounts called?
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Trace elements.
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What does an elements properties depend on?
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The structure of its atoms.
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What is the simplest portion of an element that retains its chemical properties?
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An atom.
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What are the 3 subatomic particles?
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Protons, neutrons, and electrons.
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Where in an atom are the protons and neutrons packed together?
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The nucleus.
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What does the atomic number represent?
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The number of protons in an atom.
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What are the charges of protons, neutrons, and electrons?
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Positive, neutral, and negative respectively.
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What determines the atomic mass of an atom?
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The number of protons and neutrons.
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How is the mass of the atom expressed?
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In daltons, also known as atomic mass units.
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How many grams is one dalton equal to?
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1.7 x 10^-24 grams.
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Why is the mass of electrons disregarded in calculating atomic mass?
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The electron is 1/1800 of the mass of a proton or neutron.
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What must be added to make the mass number of an atom?
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Protons and neutrons.
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What are isotopes of an element?
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Atoms that have the same number of protons and different number of neutrons.
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What is a radioactive isotope?
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An atom whose nucleus decays spontaneously, giving off particles and energy.
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What happens if an isotope gives off a proton?
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The atomic number changes and the atom becomes that of another element.
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What is energy?
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The ability to do work and cause change.
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What is potential energy?
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The energy matter has due to its location or structure.
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What does matter have the tendency to do?
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To move to the lowest possible state of potential energy.
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Why do electrons of an atom have potential energy?
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Because of how they are arranged in relation to the nucleus.
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Why does it take energy to move electrons farther away from the nucleus?
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Electrons are attracted by the positive nucleus.
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What do the fixed amounts of potential energy in an electron correspond to?
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A position at a distance from the nucleus.
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What are orbitals?
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Areas of space electrons move around the nucleus in.
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What are energy levels?
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The certain amount of energy in the electron.
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What else are energy levels referred to as?
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Electron shells.
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What is the electron configuration of the atom?
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The distribution of electrons in energy levels or shells around the nucleus.
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Do electrons that are in an energy level distant from the nucleus have more or less energy then those closer to the nucleus?
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More.
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What does the chemical behavior of an atom depend upon the most?
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The number of electrons in the outermost shell.
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What are electrons in the outermost shell called?
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Valence electrons.
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Which shell do the electrons with the greatest amount of energy occupy?
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The valence shell.
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Which elements have similar chemical properties?
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Elements with the same number of electrons in their valence shell.
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How do electrons change from one energy level to another?
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By gaining or losing energy.
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