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what is matter?
anything that takes up space, and has mass. composed of elements.
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what is an element?
composed of chemically identical atoms
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what are bulk elements?
elements that are required by the body in large amounts
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what are trace elements?
elements required by the body in small amounts
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what is an atom?
the smalles particle of an element
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atomic number
the number of protons in the nucleus of an atom
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atomic weight
the number of proton and neutrons in an atom
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what is an isotope?
- an atom with the same atomic number but with a different atomic weight
- same number of protons and electrons but different neutrons
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what is a molecule
particle formed when 2 or more atoms chemically combine
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what is a compound
particle formed when 2 or more atoms of different elements chemically bond
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when is an atom most stable?
when the outermost shell is full of electrons
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what is an ion?
- an atom that gains or loses electrons to become stable
- it is electrically charged
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what is an anion?
a negatively charged ion, formed when an atom gains electrons
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what is a cation?
a negativley charged ion, formed when an atom gains electrons
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what is an ionic bond?
- an attraction between a cation and an anion.
- when electrons are transferred between atoms
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what is a covalent bond?
formed when atoms share electrons
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polar molecules
- slightly positive and negative ends
- formed when electrons are not shared equally in covalent bonds
- Water
- Strongest
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hydrogen bond
- bond between water
- important for protein and nucleic acid structure
- Weakest bond
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when does a chemical reactions occur
when chemical bonds form or break among atoms, ions, or molecules
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reactants
the starting material of a reaction
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products
are the substances formed at the end of the chemical reaction
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synthesis reaction
A + B ---> AB
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decomposition
AB ---> A +B
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Exchange reaction or double displacement
AB + CD ---> AD + CB
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reversible reaction
- A + B <--> AB
- the products can change back to the reactants
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electrolytes
substances that release ions in water
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acids
electrolytes that dissociate to release hydrogen ions in water
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bases
substances that release ions that van combine with hydrogen ions
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salts
electrolytes formed by the reactions between and acid and a base
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what does pH mean
indicates the concentration of hydrogen ions in a solution
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what is a neutral pH
pH 7, indicateds equal concentration of H+ and OH-
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what is an acidic pH
less than 7, indicates greater concentration of H+
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what is a basic/alkaline pH
pH greater than 7, indicates a greater concentration of OH-
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how to pH levels increase
they increase in tens 10, 100, 1,000
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what do organic molecules contatin?
they contain Carbon and Hydrogen, and are usually larger than inorganic molecules
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what do organic molecules dissolve in?
in water and organic liquids
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what are some organic molecules
carbohydrates, proteins, lipids, and nucleic acid
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inorganic molecules
- generally do not contain Carbon
- usually dissociate in water forming ions
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examples of inorganic molecules
water, oxygen, carbon dioxide, and inorganic salts
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