MCAT Gen Chem 1.1

Cations

Anions

Smaller

Larger

Very large atoms with loosely held electrons...Form cations, are lustrous, ductile, malleable, and excellent conductors of both heat and electricity...they are usually only involved in ionic bonds.

Smaller atoms with loosely held electrons...Form anions, have much lower melting points than metals, and with very few exceptions, only nonmetals form covalent bonds.

Larger atoms are better at stabilizing charges, form weaker pi bonds, and have d orbitals where they can "stash" extra electrons.

Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium

Metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive.

The first of the two rows below the main part of periodic table. usually used in alloys, soft, malleable, shiny and good electrical conductors.

In the 2nd row of transition metals, radioactive, unstable, do not occur in nature.

• The amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion.
• X + e− → X−

It increases from left to right and from bottom to top

The ability of an atom to attract electrons when the atom is in a compound.



It increases from left to right and from bottom to top

The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms or ions. Large atoms or molecules have a low ionization energy, while small molecules tend to have higher ionization energies.



It increases from left to right and from bottom to top

Atomic radius gets larger from right to left and top to bottom.

Increases from right to left and top to bottom

BIG and low low ionization energy

"n" (the principle quantum number)

Gives the shell (i.e. Valence electrons are in the outermost "shell") and is approximately equal to the relative energy of electrons in that shell.

"" (the azimuthal quantum number)

• Gives the subshell: has values of 0,1,2,3 and from this were know the shape:
• 0=S ; 1=P ; 2=d ; 3=f

"m" (the magnetic quantum number)"the magnetic quantum number"

Gives the orbital; has a value of - to (from the azimuthal quantum number)

The orbital is the portion of the subshell where an electron is most likely to be found (i.e., which "dumbbell" of a p subshell)

"m_s" (the electron spin quantum number)

Gives the spin which is either +1/2 or -1/2 (Positive is up arrow or negative is down arrow)

States a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known.

The more precisely one property is measured, the less precisely the other can be controlled, determined, or known. You can know it's momentum, or where it's at, but you can't know both at the same time.

No two electrons in a single atom can have the same four quantum numbers; if n, , and m are the same, ms must be different such that the electrons have opposite spins, and so on.

If you bombard certain metals with energy, you can cause the ejection of an electron from their outermost shell (i.e. valence electron). The amount of energy required to do this is called the "work function."

This is not the same as the Ionization energy because that refers to only lone atoms in a gaseous state. The work function refers to the valence electrons being ejected from the surface of a metal.

KE = E –

• - work function variable
• KE - of the ejected electron
• E - amount of energy added

-or-

E = hf

• E - energy of a photon
• h - Planck's constant
• f - frequency

A He nucleus (2 neutrons and 2 protons) are ejected

Neutron is changed into a proton (with the ejection of an electron)

A proton is changed into a neutron via capture of an electrion

A proton is changed into a neutron (with expulsion of a positron)

Mass of one element divided by the total mass.

• 1. Change the percent for each species into grams by assuming 100g. (i.e. 17% = 17g)
• 2. Convert the grams of each species into moles by dividing by molar mass.
• 3. Look at the element with the lowest number of moles. Calculate approximately how many times it will divide into each of the other molar amounts for each of the other elements--this number is the subscript for each element in the empirical formula. If the subscripts are not at their lowest common denominator, reduce to get the empirical formula.

m = V * P

mass (g) = volume (cm3 or mL) * density (g/cm3)

Then divide mass by molecular weight to get moles.

When one atom donates both electrons to a covalent bond with another atom with a + charge.

Complex usually has a metal center.

Most common example is NH₃

Electronegativity

The more electronegative, the stronger the polarity.