Biology: Unit 2, Self Test 2
(TorF)a substance that releases hydrogen ions in water is a base
false
(TorF)of the known elements, only about ten are needed by living things.
false
if an electron is lost ], the atom has a __________________ charge.
positive
the arrangement of electrons in an atom that contains 12 electrons
2,8,2
the formula H2O means
a molecule contains 2 hydrogen atoms and 1 oxygen atom
atoms that form compounds are held together by _____________. three types can be formed. they are ______________ ____________ and ______________
bonds. ionic, covalent, and hydrogen
when two atoms combine by sharing a pair of electrons, it is a ____________ bond.
covalent
if the outer shell of the atom is full, react readily with other atoms
does not
the reactivity of an atom is due to its number and arrangement of _____________________ in the _______________ energy level (or orbit)
electrons and outer
table salt (NaCl) is a compound composed of two_____________________ , sodium and chlorine
elements or ions
(TorF)sodium and chlorine atoms combine readily because they both tend to lose electrons
false
If an atom loses an electron, it is called a/an ___________________
ion
atoms of opposite charge can combine to form a/an ____________________ bond.
ionic
if an electron is gained, the atom has a ______________________ charge.
negative
a solution containing equal numbers of hydrogen and hydroxide ions is called
neutral
(TorF) the number of protons within the nucleus of an element is called its atomic number
true
(TorF)An atom that has gained or lost electrons is called an ion
true
(TorF)a salt is produced when an acid reacts with a base
true
(TorF)the symbol Na+ represents a sodium atom that has lost an electron
true
(TorF)water is an example of a compound
true
one example of how inorganic compounds are important in biological systems is ___________________________
water