Chem Exam 1-Week 2

Remember that electrons and protons (any particle) of an atom WON’T have the same properties as it

Atomic Structure: Main types of __sub__atomic particles (electrons, protons, neutrons)

Nucleus: Neutrons and protons (most of atom’s mass)

Electron charge: negatively charged

Proton charge: positively charged

Neutron charge: no charge

Mass number: (A); number of protons and neutrons (top number)

Atomic number: (Z); number of protons (bottom number)

# protons: equal to # of electrons

No electric charge: An atom’s charge is

# of neutrons: A(mass #)-Z (atomic #)

Electron: subatomic particle provides most of atom’s volume

1 amu: the experimental value for the exact mass of one proton or one neutron is considered a relative unit of mass for the mass of an atom (atomic mass)

Proton mass= 1 (relative mass)

Neutron mass= 1 (relative mass)

Electron mass= 1/1836 (relative mass)

Isotopes= atoms of the same element (same Z) but different A

**The isotopes of an element have different masses because the mass of an atom is equal to the number of protons + the number of neutrons. All atoms of an element have the same number of protons, but if there are different numbers of neutrons, the mass of each form (i.e. isotope) will be different.**

Ne-20 and Ne-21= Example of Isotope (Neon)

20,000= How many neutrons are in 1000 atoms of Cl-37?

Small percentage: The percentage of isotopes with extra neutrons is a

Natural abundance: the percentage of certain isotopes in a natural sample of an element.

Percent of isotopes: (# of isotope atoms/ total # of atoms of that element) x 100; Y atoms of isotope

Average: (a+b+c)/3

Weighted Average: average including percentages (35%+25%+ 40%)

Electromagnetic Radiation: EMR; form of energy of transport with oscillating, perpendicular electric and magnetic fields traveling through space at the same rate in a wavelike motion.

Amplitude: Intensity of the wave

Wavelength: distance between repetitions of the sinusoidal shape (either a crest, trough, or full cycle repeats)

m, cm, nm: Units of wavelength

Frequency: # of complete cycles passing a fixed point/ unit of time

Hz, 1/s: Units of frequency

Inverse: The relationship between wavelength and frequency is

400 nm-700 nm: (Order of magnitude) wavelength range corresponding to the visible region

Quantum: the amount of electromagnetic energy that can be transferred in one pulse

Photon: a quantum of light; a “massless particle” of light

*all formulas for W, V, E for light are given per photon; practice calculating larger amounts with moles of photons