Chapters 7-12 Flashcards
How do atoms of phosphorus and Sulfur tend to appear in nature?
As bonded groups of 4 (P) and 8 (S) atoms.
What is a sigma covalent bond?
Sigma bonds are the result of orbital overlap directly
between the 2 bonded nuclei on the internuclear axis. These kinds of bonds can form when either an s orbital or p orbital overlap.
What are covalent bonds?
Bonds in which electrons are shared between two elements, not transferred.
What formula produces a square planar molecular
AX4E2
What is an empirical formula?
A formula that simply provides the ratios of the constituent elements in a compound.
What kind of molecular geometry do diatomic molecules have?
The only kind they can, a straight line.
What formula produces a tetrahedral molecular geometry?
AX4E0
What kind of molecular geometry does the formula AX2E0 have?
Linear. C02 is an example.
Who was the first to determine the weight of a molecule? When?
Jean-Baptiste Dumas, 1826.
What does each new row in the periodic table represent?
The first electron to populate a new principal energy level.
What is a molecular formula?
A formula that provides the exact number of atoms of each element in a molecule of a particular element.
What formula produces a trigonal bipyramidal molecular geometry?
AX5E0
What are Gilbert Lewis’s dates?
1875-1946.
Where do we find regions of high electron density in the valence shell of an atom?
In the orbitals holding lone pairs and in orbitals forming bonds to other atoms.
What is an electron domain?
a concerted region of electron density in the valence shell of an atom.
What is the name of the theory that describes the 3-dimensional structures of molecules?
Valence Shell Electron Pair Repulsion (VSEPR) theory.
What is a shortcoming of the molecular formula of molecules?
It doesn’t indicate how those atoms are arranged in space.
What formula produces a trigonal pyramidal molecular geometry?
AX3E1
What kind of molecular geometry does the formula AX4E1 have?
See-saw. SF4 is an example.
How does electronegativity trend on the periodic table?
The reverse of the first ionization energy, elements like fluorine having the greatest electronegativity and elements like cesium and francium having the smallest.
What formula produces a T-shaped molecular geometry?
AX3E2
What makes elements with similar properties similar?
The configuration of their valence electron shells.
What is the Pauling Scale?
The scale the measures electronegativity on a scale from 0 to 4, with 4 being fluorine.
What is the trend in the radius of the atom as it moves across rows?
Decreasing atomic radius as we move left to right; Increasing as we move right to left.
What formula produces a square pyramidal molecular
AX5E1
What kind of molecular geometry does the formula AX2E1 have?
Bent. O3 is an example.
What kind of molecular geometry does the formula AX2E2 have?
Bent. H2O is an example.
What counterbalances the size growth do to more and more electron shells?
The electrostatic attraction to the increasingly positive nucleus as more protons are added.
What formula produces a octahedral molecular
AX6E0
What is electronegativity?
It is the flip side of first ionization energy and refers to how easily a neutral atom picks up an electron.
What is the trend in the radius of the atom as it moves up or down a column?
Radius decreases as we move up a column; increases as we move down a column.
What kind of molecular geometry does the formula AX3E0 have?
Trigonal Planar. BF3 is an example.
What are polar covalent bonds?
Ones in which the shared electrons spend a bit more time around one element than the other, causing the system to have polarity.
What is the force that causes atoms to “want” to overcome electrostatic forces and get close to one another?
The powerful tendency of atoms to form valence octets.
What are the two types of covalent bonds that can form?
sigma bonds and pi bonds.
What is first ionization energy?
The amount of energy needed to remove an electron from an atom and create a cation with a +1 charge.
What important concept does VSEPR theory rest on?
The concept of electron domains.
What is it about water that allows it to dissolve a variety of salts that form ions in solution?
The polar covalent oxygen‑hydrogen bonds in water each have a partial charge separation. And the fact that water is an AX2E2 molecule means that it has a bent geometry.
How did Mendeleev choose columns for the periodic table?
By similar properties of the elements.
What kind of molecular geometry does the formula AX6E0 have?
octahedral. SF6 is an example.
What are Lewis structures?
Writing the symbol for the element with dots around it, representing the valence electrons.
What is a good definition of a chemical bond?
An energetically beneficial interaction between atoms that confines them to a fixed distance from one another in space.
What are some neutral atoms found in nature?
Argon in the atmosphere and gold in the earth.
What formula produces a trigonal planar molecular geometry?
AX3E0
What are Linus Pauling’s dates?
1901-1994.
What kind of molecular geometry does the formula AX4E0 have?
tetrahedral. CH4 is an example.
How does first ionization energy trend on the periodic table?
It increases as we move up and to the right on the table.
What are ionic bonds?
Bonds in which 2 atoms that have a tendency to form ions of opposite charge exchange electrons to form valence octets.
How much volume is occupied by one mole of gas at 1 atmosphere pressure and 0 degrees Celsius?
22.4 liters.
What are the 3 major types of chemical bonds?
ionic bonds and covalent bonds make up the extremes, and polar covalent bonds fill in the gray areas between them.
What kind of molecular geometry does the formula AX3E2 have?
T-shaped. ClF3 is an example.
What is a cation?
An atom that has lost one or more electrons, resulting in a net positive charge.
What formula produces a bent molecular geometry?
AX2E1 and AX2E2
What is an anion?
An atom that has gained one or more electrons, resulting in a net negative charge.
What is the allotrope of oxygen we encounter most commonly at the Earth’s surface?
Diatomic oxygen, two oxygen atoms joined by a double bond.
What is the order of covalent bonding?
First bond is always sigma, additional bonds are always pi.
What kind of molecular geometry does the formula AX3E1 have?
trigonal pyramidal. NH3 is an example.
What kind of molecular geometry does the formula AX5E1 have?
square pyramidal. BrF5 is an example.
What are cesium’s size properties in comparison to hydrogen?
Cesium has 133 times the mass of hydrogen but only 10 times the radius.
What is the basic idea behind Linus Pauling’s theory of orbital hybridization?
when an atom bonds, its valence orbitals can combine and average out to form any number of identical orbitals needed for bonding.
What kind of molecular geometry does the formula AX4E2 have?
square planar. XeF4 is an example.
How do atoms of Oxygen and Nitrogen tend to appear in nature?
As diatomic molecules.
What types of elements tend to form covalent bonds?
Ones with similar electronegativities.
What is a typical distance between two bonded atoms?
An angstrom or two.
What kind of molecular geometry does the formula AX5E0 have?
trigonal bipyramidal. PF5 is an example.
How would researchers like Lavoisier and Faraday discover the empirical formulae of compounds?
By combustion analysis: burning the compound in excess oxygen and measuring the results.
What formula produces a linear molecular geometry?
AX2E0
What formula produces a see-saw molecular geometry?
AX4E1
What are pi bonds?
The side‑on overlap of 2 sets of p orbitals can create a
shared space that holds 2 more sets of bonding electrons.
