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