Bonding 3.1- 3.2 Flashcards
Is bonding an empirical or theoretical concept?
Bonding is one of the most theoretical concepts in chemistry. We do not have direct visible evidence for bonds between atoms.
What did Friedrich Kekule illustrate about bonding theory?
In 1858, Friedrich Kekule illustrated a structural formula, representing a bond as a dash between bonding atoms.
What did Edward Frankland suggest about bonding theory?
In 1852 Edward Frankland stated that every element has a fixed bonding capacity.
What did Jacobus van’t Hoff and Joseph Le Bel contribute to bonding theory?
In 1874, they independently extended structural formula to 3 dimensions. They revised the theory to explain the ability of certain substances to change light as as it passes through the substance.
What did Richard Abegg Explain about bonding theory? Which scientist discovered evidence that supported Abegg’s ideas?
In 1904, he was the first to suggest that bonding capacity is related to an atom’s electron structure. Rutherford’s evidence for a nuclear atom supported this. Abegg also suggested the stability of the noble gasses was due to the number of electrons.
What did Gilbert Lewis contribute to bonding theory?
In 1916, he combined evidence of chemical formulas, the concept of valence, and the concept of stable electron numbers for atoms. Said that atoms could have stable electron numbers by sharing them or transferring them. This can only happen if the atoms are close which would result in an attractive force- covalent bond.
Valence Electron
Electrons in the highest energy level of an atom.
Ionic bond
Simultaneous attraction between positive and negative ions resulting from the transfer of one or more valence electrons.
Covalent bond
Simultaneous attraction of the nuclei of two atoms for valence electrons that they share between them.
How are electrons described in quantum mechanics?
Electrons are described in terms of their energy content, and orbitals in terms of calculated probability of an electron being at any given point relative to the atomic nucleus.
Orbital
A specific volume of space in which an electron of a certain energy level is likely to be found. Each orbital may contain two, one, or no electrons.
Bonding electron
An atom with a valence orbital that is occupied by one electron can theoretically share this electron with another atom.
Lone pair
Two electrons occupying the same orbital. This has a repelling effect on any nearby orbitals.
How many orbitals can be in the first energy level of an atom?
One orbital with a maximum of two electrons.
What element has unique properties and why?
Hydrogen is the smallest reactive atom with the simplest structure and only one energy level. This is why it is unique and is an exception to most rules and generalizations.
Energy levels above the first contain this many orbitals.
Four orbitals, maximum eight electrons.
Octet rule
A structure with eight electrons filling a valence level is very stable. The rule is usually obeyed by main group atoms but only C, N, O, F atoms always obey the rule when bonding.
The Pauli exclusion principle
Two electrons may share the same region of space at the same time (orbitals may have 0, 1, or 2 electrons).
Electronegativity
Relative ability of an atom to attract a pair of bonding electrons in its valence level.
Crystal Lattice
Ions in an ionic compound always pack together to form a repeating 3D pattern. This is called a crystal lattice because when the ions assemble , the structure is always crystalline.
A type of bonding where no chemical reaction occurs.
Metallic bonding
Why does chlorine exist as diatomic molecules
Chlorine has 7 valence electron and only requires one to obtain a stable octet. By sharing a pair of electrons, two chlorine atoms can achieve stability.
Molecular Element
Chemical species that has at least two atoms of the same element bonded to each other.
Double bond
When atoms share two pairs of electrons in a chemical bond.
Bonding capacity
The maximum number of single covalent bonds that an atom can form. It is determined by its number of bonding electrons
Coordinate covalant bond
An atom overlaps a full valence orbital (lone pair) with an unoccupied one
Ionic compound formula
Empirical formulas representing the crystal lattice with a ratio showing the simplest number of cations to anions.
Empirical formula
Shows the simplest ratio of atoms in the compound. Rarely useful for molecular compounds
Molecular formula
Shows the actual number of atoms that are covalently bonded to make up each molecule
Lewis formula
Uses Lewis symbols to show electron sharing in covalent bonds, and the formation of stable valence octets in molecules and ions
Structural formula
Shows which atoms are bonded and represents the type of covalent bond with the number of lines drawn between atomic symbols
Stereochemical formula
A structural formula drawn to try and represent the 3-D molecular shape
Central atom
Atom to which ll other (peripheral) atoms are bonded.
What did Dr. Linus Pauling explain
In 1939 he explained why certain electron arrangements are stable as well as showing that electron sharing must cover a complete range from equal attraction to total transfer. In 1954 Dr. Pauling won the Nobel prize.
Timeline of the old dudes
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