Ch. 2 - Atoms, Molecules, and Ions

Question 1

What are ions? How are charges of ions determined?

Answer 1

Ions are positively or negatively charged atoms.

1. ) Atoms of many main-group metals lose enough electrons to leave them with the same number of electrons as an atom of the preceding noble gas. Typically from groups 1 and 2; leaving a positively charged monatomic ion.
2. ) When atoms of nonmetal elements form ions, they generally gain enough electrons to give them the same number of electrons as an atom of the next noble gas in the periodic table; typically from groups 16-17.
3. )transition metals and some other metals often exhibit variable charges that are not predictable by their location in the table. For example, copper can form ions with a 1+ or 2+ charge, and iron can form ions with a 2+ or 3+ charge.

Question 2

how are Ionic bonds formed?

Answer 2

When electrons are transferred

Question 3

How are covalent bonds formed?

Answer 3

When electrons are “shared” between atoms

Question 4

What are ionic compounds?

Answer 4

1. ) When a metal is combined with one or more nonmetals, the compound is usually ionic.(not always true).
2. ) Ionic compounds are solids that typically melt at high temperatures and boil at even higher temperatures.
3. ) In every ionic compound, the total number of positive charges of the cations equals the total number of negative charges of the anions. Thus, ionic compounds are electrically neutral overall, even though they contain positive and negative ions.

Question 5

What is a Molecular Formula?

Answer 5

A molecular formula is a representation of a molecule that uses chemical symbols to indicate the types of atoms followed by subscripts to show the number of atoms of each type in the molecule. (A subscript is used only when more than one atom of a given type is present.) Molecular formulas are also used as abbreviations for the names of compounds.

A molecular formula indicates the actual numbers of atoms of each element in a molecule of the compound.

Question 6

What is a Structural Formula?

Answer 6

The structural formula for a compound gives the same information as its molecular formula (the types and numbers of atoms in the molecule) but also shows how the atoms are connected in the molecule.

Question 7

What is an Empirical Formula?

Answer 7

An Empirical Formula indicates the types of atoms present and the simplest whole-number ratio of the number of atoms (or ions) in the compound.

Question 8

What are Isomers?

Answer 8

Isomers are compounds with the same chemical formula but different molecular structures

Question 9

What are spatial and structural isomers?

Answer 9

Structural Isomers are - one of two or more compounds that contain the same number and kinds of atoms but that differ significantly in their geometric arrangement.

Spatial Isomers are - is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space.

Question 10

What is a valence shell?

Answer 10

The number of electrons in the outermost shell of a particular atom determines its reactivity, or tendency to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons. In general, atoms are most stable, least reactive, when their outermost electron shell is full.

Question 11

What is the Octet Rule?

Answer 11

Most of the elements important in biology need eight electrons in their outermost shell in order to be stable, and this rule of thumb is known as the octet rule.