Chem: Chapter 3
The force that holds atoms together is called a
Chemical Bond
A ________ is formed when atoms share electrons
Covalent Bond
A collection of atoms makes a
Molecule
Molecules can be represented using
Chemical Formula and Structural Formula
Indicates the relative sizes of the atoms as well as their relative orientation in the molecule
Space-filling model
A three-dimensional model using spheres and rods
Ball and stick method
Amount of energy needed to break a bond
Bond energy
Occurs between an atom that easily loses electrons and an atom that has a high affinity for electrons.
Ionic bonding
______ are formed when metals react with non-metals
Ionic compounds
______ is used to calculate the energy of interaction between ions
Coulomb's law
____ is defined as the distance between two atoms where the energy is the lowest
Bond length
Unequal sharing of electrons between atoms in a molecule & Resulting in a charge separation in the bond
Polar Covalent Bond
The ability of an atom in a molecule to attract shared electrons to itself
Electronegativity
As radius increases, ______ decreases
Electronegativity
As _____ gets smaller, the electronegativity increases because nucleus is closer to shared electrons
Atom
Going from _____ to ____ on a periodic table electronegativity increases
left to right
Going from ___ to ____ on a periodic table electronegativity decreases
Top to bottom
In a reaction between a nonmetal and a representative group metal a ______ is formed
Binary Ionic Compound
_____ :Same number of electrons
Isoelectronic Series
______ - Chemists term for compounds in solid state
Ionic Compound
______ tend to increase the stability of a compound
Large attractive forces
An important fact that applies is that chemical compounds are always _____
Electrically Neutral
____ influences the structure and stability of ionic solids
Ion size
____ is determined by measuring the distance between ion centers
Size
Size of the parent ion & Position in the periodic table
Factors that influence ionic size
____ are ions that contain the same number of electrons
Isoelectric ions
_____ - The change in energy that takes place when separated gaseous ions are packed together to form an ionic solid
Lattice energy
It is mostly defined as the energy released when an ionic solid forms its ions
Lattice energy
_____ - Undergoes sublimation
Sublimation endo
_____ - Atoms are ionized forming ions & energy is released
Ionization energy endo
______ - Molecules undergo dissociation
Bond cleavage endo
____ - Gaseous ions combine to form solid
Gas endo
They are used to explain how nature operates on the microscopic level based on experiences in the macroscopic world
Model
They are created by observing the properties of nature
Model
The ______ provides a framework to systematize chemical behavior & Molecules are viewed as collections of common fundamental components
Bonding model
____ - Used to calculate approximate values for reactions
Bond energies
___ can be broken when positive energy is added to the system
Bonds
A molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of the bound atoms
Localized electron model
Pairs of electrons localized on a specific atom are called ___
lone pairs
Electron pairs found in the space between the atoms are called ____
Bonding pairs
Description of the valence electron arrangement in the molecule using Lewis structures
Part of the locailzed electron model
Prediction of the geometry of the molecule using the valence shell electron-pair repulsion (VSEPR) model
Part of the locailzed electron model
Description of the type of atomic orbitals used by the atoms to share electrons or hold lone pairs
Part of the locailzed electron model
Shows how valence electrons are arranged among atoms in a molecule
Lewis Structure
Atoms achieving noble gas configurations are central to the formation of a stable compound
Lewis Structure
Only valence electrons are included
Writing lewis structure
Dots represent electrons
Writing lewis structure
____ - The first energy level (or shell) of an atom is most stable when it contains 2 electrons. This rule applies primarily to the first energy level because it can only hold a maximum of 2 electrons
Duet Rule
____ - Elements form stable molecules when surrounded by eight electrons
Octet Rule
It is the condition in which more than one valid Lewis structure can be written for a specific molecule
Resonce
Atoms need to be connected in the same order
Resonce
The resulting electron structure is derived from the average of the ____ & represented by double-headed arrows
Resonance Structure
The ______ is based on electron pairs
Localized electron model
A _____ is like a super-detailed and advanced 'map' or 'picture' that helps us understand something really well. It's made using a lot of advanced tools and information to show us a more complete and precise picture of what's going on
Sophisticated Model
It is used to estimate the charge on all possible nonequivalent Lewis structures
Formal charge
It is defined as the difference between the number of valence electrons on the free atom and the number of electrons assigned to the atom in the molecule
Formal charge
Atoms in molecules try to achieve charges as close to zero as possible
formal charges in evaluating lewis structures
Any negative formal charges are expected to reside on the most electronegative atoms
Formal charges in evaluating lewis structures
Valence electrons are assigned to various atoms based on the following assumptions
Lone pair electrons belong entirely to the atom in question & Shared electrons are divided equally between the two sharing atoms
____ : Anions that contain an atom of a given element and different numbers of oxygen atoms
Oxyanions
A bond dissociation energy is
The energy required to break a covalent bond
Single, double, or triple covalent bonds in a carbon atom are formed from
valence electrons
A single bond, compared to a double bond,
is longer
Which of the following is the strongest type of bond?
a triple bond
The best reason for why a covalent bond forms is
atoms with high electronegativities will not lose electrons, so instead they share electrons to reach a stable number of valence electrons.
A more electronegative atom
will have more attraction to the electrons in a chemical bond
In a polar covalent bond,
one atom in the bond must have higher electronegativity than the other atom.
Which one of the following statements best describes electronegativity in atoms?
Electronegativity is the attraction an element's nucleus has for the electrons in a chemical bond
Based on their positions in the periodic table, which of the following bonds is the most polar?
Polar bonds occur between two nonmetals and have a difference in electronegativities of the atoms. The further apart two atoms are in the same period, the greater the polarity of the bond.
Determine partial positive charge
Partial charges are determined by the relative electronegativities of the atoms in a molecule; since you are looking for the atom with a positive partial charge, you should choose the atom that is the least electronegative.
Which one of the following is the least electronegative atom?
Alkali metals and alkaline earth metals have lower electronegativities.
A lattice energy is
the amount of energy that must be supplied to break an ionic solid into its individual gaseous ions.
Which one of the following trends appears when considering lattice energies?
The higher the charge on the ions, the higher the lattice energy.