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2.1 Elements and atoms: the building blocks of matter Read Online
2.2 Chemical bonds Read Online
2.3 Chemical reactions Read Online
2.4 Inorganic compounds essential to human functioning Read Online
2.5 Organic compounds essential to human functioning Read Online
After studying this chapter, you will be able to:
The smallest, most fundamental material components of the human body are basic chemical elements. In fact, chemicals called nucleotide bases are the foundation of the genetic code with the instructions on how to build and maintain the human body from conception through old age. There are about three billion of these base pairs in human DNA.
Human chemistry includes organic molecules (carbon-based) and biochemicals (those produced by the body). Human chemistry also includes elements. In fact, life cannot exist without many of the elements that are part of the earth. All of the elements that contribute to chemical reactions, to the transformation of energy, and to electrical activity and muscle contraction—elements that include phosphorus, carbon, sodium, and calcium, to name a few—originated in stars.
These elements, in turn, can form both the inorganic and organic chemical compounds important to life, including, for example, water, glucose, and proteins. This chapter begins by examining elements and how the structures of atoms, the basic units of matter, determine the characteristics of elements by the number of protons, neutrons, and electrons in the atoms. The chapter then builds the framework of life from there.
Question: Nitrogen has an atomic number of seven. How many electron shells does it likely have?
Choices:
one
two
three
four
Question: The characteristic that gives an element its distinctive properties is its number of ________.
Choices:
protons
neutrons
electrons
atoms
Question: On the periodic table of the elements, mercury (Hg) has an atomic number of 80 and a mass number of 200.59. It has seven stable isotopes. The most abundant of these probably have ________.
Choices:
about 80 neutrons each
fewer than 80 neutrons each
more than 80 neutrons each
more electrons than neutrons
Question: When an atom donates an electron to another atom, it becomes
Choices:
an ion
an anion
nonpolar
all of the above
Question: Together, just four elements make up more than 95 percent of the body's mass. These include ________.
Choices:
calcium, magnesium, iron, and carbon
oxygen, calcium, iron, and nitrogen
sodium, chlorine, carbon, and hydrogen
oxygen, carbon, hydrogen, and nitrogen
Question: The energy stored in a foot of snow on a steep roof is ________.
Choices:
potential energy
kinetic energy
radiant energy
activation energy
Question: A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with ________.
Choices:
ionic bonds
nonpolar covalent bonds
polar covalent bonds
hydrogen bonds
Question: The smallest unit of an element that still retains the distinctive behavior of that element is an ________.
Choices:
electron
atom
elemental particle
isotope
Question: Which of the following is a molecule, but not a compound?
Choices:
H2O
2H
H2
H+
Question: Which of the following statements about chemical bonds is true?
Choices:
Covalent bonds are stronger than ionic bonds.
Hydrogen bonds occur between two atoms of hydrogen.
Bonding readily occurs between nonpolar and polar molecules.
A molecule of water is unlikely to bond with an ion.
Question: A substance formed of crystals of equal numbers of cations and anions held together by ionic bonds is called a(n) ________.
Choices:
noble gas
salt
electrolyte
dipole
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