Ionic and Covalent Bonding Flashcards
1
Q
Chemical Bonding
A
- attractive forces that hold atoms together in compounds
- Three types of chemical bonding
- Ionic Bonding
- Covalent Bonding
- Metallic Bonding
2
Q
Ionic Bonds
A
- Also known as Electrovalent bond
- Chemical bond formed by the electrostatic attraction between positive and negative ions.
- Bonds result from transfer of valence shell electrons from one atom to another.
- Atoms that lose electrons, becomes cations
- Atoms that gain electrons, becomse anion
- purpose is to acquire a noble gas configuration.
- Favored when
- low ionization energy + large negative electron affinity
- metal element + non-metal element.
3
Q
Covalent Bond
A
two atoms share valence electrons, which are attracted to the positively charged cores of both atoms.
4
Q
Metallic Bond
A
The metal is held together by the strong forces of attraction between the positive nuclei and the delocalized electrons.
5
Q
Octet Rule
A
- Most elements follow the octet rule in which the purpose of chemical bonding is to aquire a noble gas electron configuration.
- Exceptions:
- H, Li, Be follow the duet rule, they aquire the He electron configuration
- Octet rule is less applicable to the transitional elements.
6
Q
Lewis Electron Dot Symbols
A
- a symbol in which the electrons in the valence shell of an atom or ion are represented by dots placed around the letter symbol of the element.
- Lewis developed it for covalent bonds, but can use for ionic bonds.
7
Q
Lattice Energy
A
- the change in energy that occurs when an ionic solid is seperated into isolated ions in the gas phase.
- the formation of 1 mol of an ionic solid from its seperate ions
- measure of the strength of the crystal’s ionic bonds
8
Q
Born-Haber Cycle
A
- Application of Hess’s law to ionic solids.
- Although the reaction happens occur all at once, it is easier to obtain energy calculations stepwise.
- Hypothetical multistep process (5 steps)
- Sublimation of sodium
- Dissociation of chlorine
- Ionization of sodium
- Formation of chloride ions
- Formation of NaCl(s) from ions
9
Q
What is the energy involved in ionic bonding?
A
- strong forces arising from electrostatic attraction
- Coulomb’s law is used to measure the energy involved in the interaction of electric charges.
- Formula: E = (kQ1Q2)/r
- where: r = distance
- k = constant: 8.99 x 109 J•m/C2
- Q1 = charge on one element
- Q2 = charge on second element
10
Q
What are the properties of Ionic Substances?
A
- solids with high melting points, the higher the charge the higher the melting point.
- molten compounds and aqueous solutions conduct electricity well because they contain mobile charged particles.
- are soluble in polar solvents. i.e. water.
11
Q
Electron configuration for an anion.
A
- add electrons to the valence shell of the neutral nonmetal atom without adding protons or neutrons to the nucleus.
- number of electrons gain, is usually enough to complete the valence shell of the atom
12
Q
Electron configuration for a cation
A
- a metal atom loses one or more electrons in forming a cation.
- the “p” valence electrons (if they are any) are lost first and then “s” valence electrons in some cases, “d” electrons of the next two outermost shell follow.
13
Q
Electron configuration for Transitional metal ions
A
- can form several cations of different charges
- first electrons lost are in the ‘s’ then one or more in the (n-1)d electrons. most have the +2 charge because of loss of ‘s’ electrons.
- colors of the transitional element ions are due to the ‘d’ electrons.
14
Q
Ionic Radii
A
- measure of the size of the spherical region around the nucleus of an ion within which elecrons are most likely to be found.
- Radii can be obtained by crystal structure studies or x-ray diffraction.
- Cations are smaller than the atoms from which they are formed because of the loss of valence shell
- Anions are larger than the atoms from which they are formed because of the gain of electrons.
- Generally decrease in radii across the period and increase down the group.
15
Q
Isoelectronic
A
- refers to different species having the same number and configuration of electrons. e.g. Ne, Na+ and Mg2+ have the same configuration of electrons.
- for a series of isoelectronic species with the same electron configuration, the greater the charge, the smaller the species.
16
Q
Lewis Electron Dot Formula
A
Using dots to represent valence electrons