Prentice Hall Biology

Front 1

What three subatomic particles make up atoms?

Back 1

Protons, Neutrons and Electrons

Front 2

How are all of the isotopes of an element similar?

Back 2

Because they have the same number of electrons, all isotopes of an element have the same chemical properties.

Front 3

What are the two main types of chemical bonds?

Back 3

The main types of chemical bonds are ionic bonds and covalent bonds.

Front 4

Helium atoms contain protons, neutrons, and electrons. The positively charged protons and unchanged neutrons are bound together in the dense nucleus, while the negatively charged electrons move in the space around the nucleus.

Back 4

Helium
Atomic number = 2
Mass number = 4

Front 5

Because they have the same number of electrons, these isotopes of carbon have the same chemical properties. The difference among the isotopes is the number of neutrons in their nuclei.

Back 5

Nonradioactive carbon-12
6 electrons
6 protons
6 neutrons

Nonradioactive carbon-13
6 electrons
6 protons
7 neutrons


Nonradioactive carbon-14
6 electrons
6 protons
8 neutrons

Front 6

What information is contained in a chemical formula?

Back 6

Scientists show the composition of compounds by a kind of shorthand known as a chemical formula. Water, which contains two atoms of hydrogen for each atom of oxygen, has the chemical formula H2O. The formula for table salt. NaCl, indicates that the elements from which table salt forms - sodium chlorine - combine in a 1:1 ratio.

Front 7

The chemical bond in which electrons are transferred from one atom to another is called an ionic bond. The compound sodium chloride forms when two sodium loses its valence electron to chlorine.

Back 7

Chlorine atom (Cl)
Protons +17
Electrons -17
Charge = 0

Sodium ion (Na+)
Protons +11
Electrons -10
Charge = +1

Chloride ion (Cl+)
Protons +17
Electrons -18
Charge = -1

Front 8

Figure 2 -4 Water Molecule

Back 8

The chemical bond in which electrons are shared between atoms is called a covalent bond. In a water molecule, each hydrogen atom shares two electrons with the oxygen atom.

Front 9

Figure 2 -5 Van der Waals forces help geckos grip smooth, vertical surfaces. How do van der Waals's forces hold molecules together?

Back 9

When molecules are close together, a slight attractions can develop between the oppositely charged regions of nearby molecules. Chemists call intermolecular forces of attraction van der Waals forces, after the scientis who discovered them. Although ven der Waales forces are not as strong as ionic bonds or covalent bonds, they can hold molecules together, especially when the molecules are large.