ANATOMY
CHEMISTRY FOR
PHYSIOLOGY
NOTES,
QUESTIONS AND
ANSWERS
,4.1 Atoms and Molecules 1
Chemistry for Physiology
Atoms and Molecules
There are 90 naturally occurring simplest substances called chemical “elements”.
The smallest particle of an element is called an atom of that element. The names of
these elements are shortened to one or two-letter symbols that are displayed on the
“periodic table”. Metal elements (e.g. Na, Ca, K) appear on the left while non-metal
elements (e.g. Cl, O, N) appear on the right hand side of this table. A metal element
may react with a non-metal element to form a new substance which will be a type
of “ionic” compound. A non-metal element may react with another non-metal
element to form a new substance which will be a type of “covalent” compound.
Ionic compounds in solid form, are continuous lattice structures, which when they
dissolve, allow the particles move about separately as positive ions if they have lost
an electron(s) or negative ions if they gained electron(s). Covalent compounds exist
as groups of atoms (known as molecules), with a fixed ratio of different atoms. The
atoms in these molecules stay together. Examples are H2O (water), C6H2O6
(glucose), CO2 (carbon dioxide), CH3COOH (acetic acid). Ions and small molecules
such as these, and amino acids and lipid molecules are able to move into and out of
cells through the plasma membrane during normal cell functioning.
On a macroscopic scale, humans are a skinful of solids and liquids with no spaces
(molecules and ions are “shoulder to shoulder”). However on the sub atomic scale,
atoms are mostly empty space! If the central nucleus (which consists of 2 types of
particle called protons and neutrons) of an atom was the size of a tennis ball, the
whole atom would have a diameter of about 600 m with just a few electrons
occupying the mostly empty space which surrounds the “tennis-ball-sized” nucleus.
Therefore humans are mostly empty space surrounding the nuclei of our atoms.
1. The chemical formula C6H12O6 contains much information. However, what
information is NOT provided by the formula?
A. the number of atoms in a molecule
B. the name of the substance
,4.1 Atoms and Molecules 2
C. the elements that make up the substance
D. whether the substance is covalent or ionic
Answer is B: the name may be guessed at, but it is possible for two substances to
have the same formula but a different structure.
2. Which of the particles listed below is the smallest?
A. an atom
B. a proton
C. an ion
D. a molecule
Answer is B: a proton is a sub-atomic particle so is smaller than all of the others
3. The chemical name for sodium is which of the following?
A. Na
B. So
C. K
D. Si
Answer is A: Na is short for Natrium which is the Latin name for sodium.
4. A molecular compound may be defined by which of the following?
A. atoms from non-metal elements covalently bonded.
B. atoms from metal elements covalently bonded
C. atoms from metal elements and non-metal elements covalently bonded
D. atoms from non-metal elements ironically bonded
Answer is A: only non-metal elements are involved in covalent (molecular)
bonding.
5. Many drugs are neutralised to form salts and administered in this form. What
is the main advantage of administering the salt form of the drug? It is usually:
A. less toxic
B. more soluble in water
C. more pleasant to taste
D. more soluble in lipid
Answer is B: salts, having particles that are electrically charged, are more likely to
be soluble in water.
6. One of the following is INCORRECT. Which one?
A. metal atoms will form compounds with non-metal atoms.
B. metal atoms will form compounds with metal atoms.
C. non-metal atoms will form compounds with non-metal atoms.
D. metal atoms will not form compounds with metal atoms.
, 4.1 Atoms and Molecules 3
Answer is B: metal atoms can only form (ionic non-molecular) compounds with
non-metal atoms.
7. Choose the correct statement about hydrogen bonds. They
A. are stronger than covalent bonds.
B. act between the H in one –OH or –NH group, and the O or N in another.
C. operate within molecules.
D. act between the H in one –OH or –NH group, and the H in another.
Answer is B: the slightly positive H atom in one molecule is attracted to the adjacent
slightly negative O (or N).
8. Given that the atomic mass of nitrogen is 14 and of hydrogen is 1, what is the
mass in grams of one mole of ammonia (NH 3)?
A. 15 B. 16 C. 17
D. 18
Answer is C: from the formula, there is one N and three H atoms. So
(1 × 14) + (3 × 1) = 17.
9. Choose the ending that will correctly complete the sentence: When atoms of a
metal element and atoms of a non-metal element react, the result is
A. a covalent compound consisting of molecules
B. a covalent compound consisting of ions
C. an ionic compound consisting of ions in a lattice
D. an ionic compound consisting of molecules in a lattice
Answer is C: atoms of a metal element react with atoms of a non-metal element to
form an ionic compound (ions held within a lattice when in solid form).
10. In a water molecule, the bond between oxygen (O) and hydrogen (H) is
A. a covalent bond and a polar bond
B. an ionic bond
C. a covalent bond
D. an ionic bond and forms an electrolyte
Answer is A: as both atoms are non-metals, the bonding is covalent. As the atoms
differ in their attraction for the bonding electrons, the bond is polar (the electrons
are more closely attracted to O).
11. Some atoms of potassium, K contain 19 protons and 20 neutrons in their nuclei.
What is the correct symbol for these atoms?
A. 1920K
B. 1920K C. 1939K
D. 2039K
CHEMISTRY FOR
PHYSIOLOGY
NOTES,
QUESTIONS AND
ANSWERS
,4.1 Atoms and Molecules 1
Chemistry for Physiology
Atoms and Molecules
There are 90 naturally occurring simplest substances called chemical “elements”.
The smallest particle of an element is called an atom of that element. The names of
these elements are shortened to one or two-letter symbols that are displayed on the
“periodic table”. Metal elements (e.g. Na, Ca, K) appear on the left while non-metal
elements (e.g. Cl, O, N) appear on the right hand side of this table. A metal element
may react with a non-metal element to form a new substance which will be a type
of “ionic” compound. A non-metal element may react with another non-metal
element to form a new substance which will be a type of “covalent” compound.
Ionic compounds in solid form, are continuous lattice structures, which when they
dissolve, allow the particles move about separately as positive ions if they have lost
an electron(s) or negative ions if they gained electron(s). Covalent compounds exist
as groups of atoms (known as molecules), with a fixed ratio of different atoms. The
atoms in these molecules stay together. Examples are H2O (water), C6H2O6
(glucose), CO2 (carbon dioxide), CH3COOH (acetic acid). Ions and small molecules
such as these, and amino acids and lipid molecules are able to move into and out of
cells through the plasma membrane during normal cell functioning.
On a macroscopic scale, humans are a skinful of solids and liquids with no spaces
(molecules and ions are “shoulder to shoulder”). However on the sub atomic scale,
atoms are mostly empty space! If the central nucleus (which consists of 2 types of
particle called protons and neutrons) of an atom was the size of a tennis ball, the
whole atom would have a diameter of about 600 m with just a few electrons
occupying the mostly empty space which surrounds the “tennis-ball-sized” nucleus.
Therefore humans are mostly empty space surrounding the nuclei of our atoms.
1. The chemical formula C6H12O6 contains much information. However, what
information is NOT provided by the formula?
A. the number of atoms in a molecule
B. the name of the substance
,4.1 Atoms and Molecules 2
C. the elements that make up the substance
D. whether the substance is covalent or ionic
Answer is B: the name may be guessed at, but it is possible for two substances to
have the same formula but a different structure.
2. Which of the particles listed below is the smallest?
A. an atom
B. a proton
C. an ion
D. a molecule
Answer is B: a proton is a sub-atomic particle so is smaller than all of the others
3. The chemical name for sodium is which of the following?
A. Na
B. So
C. K
D. Si
Answer is A: Na is short for Natrium which is the Latin name for sodium.
4. A molecular compound may be defined by which of the following?
A. atoms from non-metal elements covalently bonded.
B. atoms from metal elements covalently bonded
C. atoms from metal elements and non-metal elements covalently bonded
D. atoms from non-metal elements ironically bonded
Answer is A: only non-metal elements are involved in covalent (molecular)
bonding.
5. Many drugs are neutralised to form salts and administered in this form. What
is the main advantage of administering the salt form of the drug? It is usually:
A. less toxic
B. more soluble in water
C. more pleasant to taste
D. more soluble in lipid
Answer is B: salts, having particles that are electrically charged, are more likely to
be soluble in water.
6. One of the following is INCORRECT. Which one?
A. metal atoms will form compounds with non-metal atoms.
B. metal atoms will form compounds with metal atoms.
C. non-metal atoms will form compounds with non-metal atoms.
D. metal atoms will not form compounds with metal atoms.
, 4.1 Atoms and Molecules 3
Answer is B: metal atoms can only form (ionic non-molecular) compounds with
non-metal atoms.
7. Choose the correct statement about hydrogen bonds. They
A. are stronger than covalent bonds.
B. act between the H in one –OH or –NH group, and the O or N in another.
C. operate within molecules.
D. act between the H in one –OH or –NH group, and the H in another.
Answer is B: the slightly positive H atom in one molecule is attracted to the adjacent
slightly negative O (or N).
8. Given that the atomic mass of nitrogen is 14 and of hydrogen is 1, what is the
mass in grams of one mole of ammonia (NH 3)?
A. 15 B. 16 C. 17
D. 18
Answer is C: from the formula, there is one N and three H atoms. So
(1 × 14) + (3 × 1) = 17.
9. Choose the ending that will correctly complete the sentence: When atoms of a
metal element and atoms of a non-metal element react, the result is
A. a covalent compound consisting of molecules
B. a covalent compound consisting of ions
C. an ionic compound consisting of ions in a lattice
D. an ionic compound consisting of molecules in a lattice
Answer is C: atoms of a metal element react with atoms of a non-metal element to
form an ionic compound (ions held within a lattice when in solid form).
10. In a water molecule, the bond between oxygen (O) and hydrogen (H) is
A. a covalent bond and a polar bond
B. an ionic bond
C. a covalent bond
D. an ionic bond and forms an electrolyte
Answer is A: as both atoms are non-metals, the bonding is covalent. As the atoms
differ in their attraction for the bonding electrons, the bond is polar (the electrons
are more closely attracted to O).
11. Some atoms of potassium, K contain 19 protons and 20 neutrons in their nuclei.
What is the correct symbol for these atoms?
A. 1920K
B. 1920K C. 1939K
D. 2039K
