Ch.2 Concepts & Connections Flashcards
describe the importance of chemical elements to living organisms
chemicals are the very stuff making up our bodies, those of other organisms and the physical environment around us. cells, tissues and organs are made of chemical compounds: the elements that make up living matter and the ways in which the atoms of those elements interact
explain the formation of compounds
a substance consisting of two or more different elements combined in a fixed ratio. compounds are much more common than pure elements
describe the structure of an atom
is the smallest unit of matter that still retains the properties of an element. atoms consist of a proton(+), a neutron and a electron (-)
distinguish between ionic, hydrogen, and covalent bonds
ionic bonds:2 ions w/opposite charges attract, when this attraction holds them together it is called an ionic bond. hydrogen bonds: weak bonds but very important and prominent in water bonds. covalent bonds:is the strongest type of chemical bond in which 2 atoms share 1 or more pairs of outer shell electrons.
define a chemical reaction and explain how it changes the composition of matter
the breaking and making of chemical bonds is a chemical reaction, leading to changes in the composition of matter which is the conversion of the starting material (reactants) to the product.
list and define the life-supporting properties of water
hydrogen bonds make liquid water cohesive.this tendency of molecules of the same kind sticking together is called cohesion. adhesion is the clinging of one substance to another (roots of trees). surface tension is a measure of how difficult it is to stretch or break the surface of a liquid.
explain the pH scale and the formation of acid and base solutions
a compound that donates hydrogen ions to solutions is called an acid (high on the pH scale=small number). a base is a compound that accepts hydrogen ions and removes them from solution (low on the pH scale=high number).
