Chapter 5 Flashcards
The compound that forms ionic bonds is an __________.
ionic compound
The compound that forms covalent bonds is a __________.
molecular compound
The chemical formula for an ______________ lists:
- the type of atom present and
- the lowest whole number ratio of atoms present
ionic compounds
The chemical formula for a _______________ lists:
- the types of atoms present and
- the exact number of atoms present, regardless of the numbers involved.
molecular compound
Unlike ionic compounds, the clustering of _____ atoms have a unique 3-D shape.
nonmeta
A _______ is basically the limit of physical subdivision where a single entity retains all of the properties of the original group of molecules.
molecule
_______ ______ are formed when two atoms share electrons rather than transfer or accept them.
Covalent bonds
A ____________ is formed by an unequal sharing of electrons.
polar covalent bond
_________ describes the affinity or attraction that the nucleus of a given atom has for a shared pair of electrons in a covalent bond.
Electronegativity
_______ want electrons and therefore have relatively high electronegativities.
nonmetals
______ don’t need the electrons and therefore have very low electronegativities.
metals
What is the bond type when the electronegativity difference is 0?
pure or true covalent
What is the bond type when the electronegativity difference is <0 - 0.4?
nonpolar covalent
What is the bond type when the electronegativity difference is <0.4 - 1.5?
polar covalent
What is the bond type when the electronegativity difference is <1.5 and <2.0?
polar covalent - between 2 nonmetals that show 3-D molecular shape
What is the bond type when the electronegativity difference is <1.5 and <2.0?
ionic - between metal and nonmetal with no 3-D shape in the compound
What is the bond type when the electronegativity difference is 2.0 or greater?
ionic
When H is listed as the first element in a compound, it usually signifies that the compound is ______ to some degree.
acidic
What are the 2 factors that lead to polarity and must be present before a molecule will behave as a polar species?
- Polar bonds must be present in the molecule.
2. The shape of the molecule cannot be symmetrical with respect to the polar bonds.
TRUE or FALSE:
Nonmetal atoms of the same type will often bond with each other.
True
How are molecular compounds different from ionic compounds?
Molecules have unique 3-D shapes with atoms oriented in fixed positions in space. Ionic compounds form from a repeating lattice structure of alternating cations and anions – there is really no unique molecular structure in the ionic substance.
A chemical formula of an ionic compound shows the _________ ratio of ions.
lowest whole number
A chemical formula of a molecular compound shows the ______ number of atoms.
exact
TRUE or FALSE:
Molecular compounds are very different from ionic compounds.
true
If you were able to take a pure sample of water and divide it in half again and again, what would be the limit of this subdivision process where the last piece of water still behaved like water?
a single water molecule
The formula for a covalent compound must describe the actual number of atoms found in one ________ of the substance.
molecule
Covalent bonds result from the _______ of a _____ of electrons between atoms.
sharing a pair
The valence electrons are the _______ to transfer or share in chemical bonds.
easiest
Covalent bonding must involve the ______ shell electrons.
valence
TRUE or FALSE:
It is reasonable that the valence electrons are involved in chemical bonds since they are the outermost electrons and they must come in contact first when atoms come together.
true
Do covalent bonds, formed among nonmetal atoms, tend to obey or disobey the octet rule?
obey
Some chemical bonds have characteristics of both _____ and ______ bonds.
ionic and covalent
Unequal sharing of electrons leads to the formation of ___________.
polar covalent bonds
Who came up with the idea of electronegativity?
Linus Pauling
What is the most electronegative element and what is it’s value?
F (Fluorine) is 4.0
Why don’t noble gases have an electronegative value?
They have a full outer shell and don’t form bonds with other elements.
Metals have _____ electronegativities and nonmetals have ______ electronegativities.
low;
high
Given the electronegativity values of the following atoms, describe the characteristic of the chemical bond formed between them: Na (0.9) and Cl (3.0)
NaCl is ionic at a value of 2.1 - metal with nonmetal
The major character of a chemical bond is defined by a difference in the _________ of the atoms involved.
electronegativity
Describe the characteristic of the chemical bond formed between H (2.1) and F (4.0).
HF - polar covalent bond at a value of 1.9 - 2 nonmetal atoms
Describe the characteristic of the chemical bond formed between C (2.5) and O (3.5).
CO - polar covalent at a value of 1.0
Under what circumstances will 2 atoms form a pure covalent bond?
When atoms involved are identical and have the same electronegativity.
Polar covalent bonds with small differences in electronegativity behave a lot like __________.
pure covalent bonds
Molecular structure is a strong indication that the bonds have ___________ character.
covalent
Why is it hard to name covalent compounds?
They do not form predictable associations with other atoms and there are billions of these compounds in nature
Which atom is listed first in a simple binary compound that is not acidic?
least electronegative atom
What is the greek prefix that means three?
tri-
When are the number of H atoms not included in the name of the compound?
When it is listed first in the formula (acidic)
What 2 factors lead to molecular polarity?
the presence of polar bonds and the asymmetrical shape
