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Chem 3.1-3.7
Question | Answer |
---|---|
pure substances | type of matter that has a definite composition |
elements | simplest pure substances because they are composed of only are kind of atom |
compounds | two or more elements in the same proportion |
mixtures | two or more substances that are pysically mixed, but not chemically combined |
types of mixtures | homogeneous & heterogeneous |
homogeneous mixture | aka solution; composition is uniform throughout a sample (salt water) |
heterogeneous mixtures | components do not have a uniform composition throughout the sample (oil & water, raisins in a cookie) |
chemical symbols | one- or two-letter abbreviations for the names of the elements |
physical properties | characteristics that can be observed or measured w/o affecting the identity of an element (shape, color, odor, taste, density, hardness, melting point, boiling point) |
periodic table | the arrangement of elements created by Dmitri Mendeleev |
period | horizontal rows in the periodic table |
group | vertival columns on the periodic table |
atom | the smallest particle of an element that retains the characteristics of that element |
nucleus | positively charged region at the center of the atom |
amu (atomic mass unit) | used in expressing masses of neutrons, protons, ect |
atomic number | equal to the protons |
mass number | protons + neutrons= mass number |
isotopes | atoms of the same element that have different numbers of neutrons |
atomic mass | average of the mass of isotopes of an elements |
valence electrons | outermost electrons |
group numbers | (1A-8A); indicates the number of valence electrons in an element |
atomic radius | the distance from the nucleus to the valence electrons |
ionization energy | energy needed to remove the least tightly bounded electron from an atom in the gaseous state. |