General Chemistry Midterm 1

Atoms

Submicroscopic particles, fundamental building blocks of matter

Molecules

Consists of two or more atoms

Neutron

• Neutral charge

• similar mass to protons

• Located inside the nucleus

Proton

• positive charge

• Located inside the nucleus

Electron

• negative charge

• Located outside the nucleus

Atomic number (Z)

Number of protons

Mass number (A)

Sum of protons and neutrons

Isotopes

Atoms with the same number of protons but a different number of neutrons

Natural abundance

The relative amount of each different isotope in a naturally occurring sample of a given element is roughly constant (percentage)

Atomic mass

Average mass of the isotopes

Atomic mass= (natural abundance%/100)(mass of isotope) + (natural abundance%/100)(mass of isotope)

Ions

Atoms that can lose or gain electrons and become charged particles

Cations

Positively charged ions (metals)

Anions

Negatively charged ions (nonmetals)

Pure substance

Made up of only one component

Mixture

Made of two or more components

Heterogeneous mixture

The composition varies from one area to another

Homogeneous mixture

Made of multiple substances, but looks like one substance

Uncertainty principle

The more accurately you know the position of a small particle, such as an electron, the less you know about its speed, and vice versa

Orbital

A probability distribution map of a region where the electron is likely to be found

Quantum numbers

Size, shape, and orientation in space of an orbital are determined by three integers

Principal quantum number, n, energy level

• n can be any whole number integer ≥ 1

• l can have integer values from 0 to (n-1)

• s, p, d, f

• sharp, principal, diffuse, fundamental

Magnetic quantum number, ml, position

• specifies the orientation of the orbital

• Values are integers from -l to +l

• Including zero

  • Ex) l=2 ml= -2, -1, 0, +1, +2, five orbitals with l=2

s orbital, l=0

Each principal energy level has one s orbital

p orbital, l=1

• Principal energy state above n=1 has 3 p orbitals

  • ml= -1, 0, +1

d orbital, l=2

• principal energy state above n= 2 d orbitals

  • ml= -2, -1, 0, +1, +2

f orbital, l=3

• principal energy state above n=3 has 7 f orbitals

  • ml= -3, -2, -1, 0, +1, +2, +3

Electron configuration

• A description of the orbitals occupied by electrons

• Electrons occupy orbitals so to minimize the energy of the atom

Spin

• Spin up ↑, spin down ↓

• ms values of +1/2 or -1/2

Aufbau principle

Energy levels and sub levels fill from lowest energy to highest (s→p→d→f)

Valence electrons

The electrons in all the sub levels with the highest principal energy shell

Core electrons

Electrons in lower energy shells

Finding valence electrons

Electrons in the outermost principal energy level

Charge of ion based on location in the periodic table

• metals form cations (positive)

  • Alkali metals (1A) +1 cations

  • Alkaline earth metals (2A) +2 cations

• Nonmetals form anions (negative)

  • Halogens (7A) -1 anions

  • Other nonmetals, variety of charged anions

Ion size

For each negative charge is another electron gained potentially making the ion larger, less protons also make a larger radius

Empirical formula

Gives the relative number of atoms of each element in a compound

Molecular formula

Gives the actual number of atoms of each element in a molecule of a compound

Ex) C4H8 common factor= 4 CH2

Ionic compounds

Composed of cations (metals) and anions (nonmetals) bound together by ionic bonds

• the sum of the charges of the positive ions must equal the sum of the charges of the negative ions

Type 1 Cations, Binary compounds

Contain only two different elements

cation (metal) and anions (nonmetal) + -ide

Type 2 Binary Ionic Compounds

Tend to have multiple charges, charge must be written in the name (in parentheses)

Ex) Cu2O copper (II) oxide

Cation (metal) charge anion (nonmetal) + -ide

Polyatomic ions

Most are oxyanions, anions containing oxygen and another element

• if there are two, the one with more oxygen atoms ends in -ate, the one with less ends in -ite

Hydrated ionic compounds

Hydrates, contain a specific number of water molecules

Naming binary molecular compounds

Prefix + first element prefix + second element

Mono=1 Hexa=6

Di=2 Hepta=7

Tri=3 Octa=8

Tetra=4 Nona=9

Penta=5. Deca=10

Mol

6.022 × 10²³ (Avogadro’s Number)

Molar mass

The mass of 1 mol of atoms or molecules of an element, equal to the element’s atomic mass

Formula/molar mass= (# of atoms of element 1 x atomic mass of element 1) + ( # of atoms of element2 x atomic mass of element 2) + …

Electronegativity

• 0= pure colvalent

• 0.1-0.4= non polar

• 0.5-1.9= polar

• 2+= ionic