Chapter 02: Atoms and Elements Flashcards
Law of conservation of mass
Matter is neither created nor destroyed in a chemical reaction
Mass of reactants = mass of products
Law of definite proportions
All samples of a given compound have the same proportions of their constituent elements
Water is always H20
Law of multiple proportions
Atoms of two or more elements may combine in different ratios, producing various compounds
Subatomic particles
Election (e-) - negative charge, mass is minute
Proton (p) - positive charge, mass = 1840x an electron’s
Neutron (n) - neutral particle, GREATEST MASS
Cathode rays
Beam of particles, negatively charged
Cathode
Negatively charged electrode
Anode
Positively charged electrode
Radioactivity
Spontaneous emission of particles and/or radiation
Radioactive element
Spontaneously emits radiation
Alpha particles
Positively charged particles
Beta particles
Negatively charged particles
Gamma rays
Neutral charge, high-energy radiation
Nuclear theory
Nucleus = most of atom’s mass and all of its positive charge
Empty space = most of the atom
of protons = # of electrons, so atoms are neutral
Periodic table
Elements are in order of increasing atomic number
Row = period Column = group/family
Group 1A
Alkali metals
Group 2A
Alkaline earth metals
Groups XB
Transition metals
Groups XB - inserted rows
Inner transition metals
Group 7A
Halogens
Group 8A
Noble/inert gases
Atomic number
Z
Number of protons
Mass number
A
Number of protons + neutrons
Chemical symbol
X
Chemical abbreviation
X-A
Chemical-Mass #
Molecule
2+ atoms in DEFINITE arrangement, held together by chemical forces
Diatomic molecule
2-atom molecule
Diatomic molecules in nature (7)
Hydrogen (H) Nitrogen (N) Fluorine (F) Oxygen (O) Iodine (I) Chlorine (Cl) Bromine (Br)
H + N through F + F down to I
“Have No Fear Of Ice Cold Beer”
Polyatomic molecule
> 2 atom molecule
Polyatomic molecules in nature
Phosphorus (P4)
Sulfur (S4)
Selenium (Se4)
(Oxygen (O3))
(remaining 3 Other Nonmetals angled in diatomic molecules N, O, F, Cl, Br
Cation
Positively charged ion
Anion
Negatively charged ion
Monatomic ion
1-atom ion
Polyatomic ion
2+ atom ion
Main-group/representative elements
A groups
Properties tend to be largely predictable based on location in table
Transition elements
B groups
Properties tend to be less predictable simply based on location in table
Metals
Solids at room temperature (EXCEPT MERCURY, Hg) Lustrous (shiny) Good conductors of heat/electricity Malleable Ductile High melting points, high densities Tends to lose electrons
Form ionic compounds with nonmetals
Rarely combine with other metals
Metals found in free states (3)
“Noble metals”
Silver (Ag)
Platinum (Pt)
Gold (Au)
Nonmetals
Not lustrous (shiny) Poor conductors of heat/electricity Not malleable Not ductile Fairly low melting points & densities Tend to gain electrons
Form molecular compounds with each other (and metalloids)
Form ionic compounds with metals
BROMINE (Br) is liquid at room temperature
Metalloids
Properties are between metals and nonmetals
Some are semiconductors
Boron (B) through Astatine (At) EXCLUDING Aluminum (Al) (and Polonium (Po))
Transition metals with predictable charge (3)
Silver (Ag) - Group 1B = 1+ charge
Zinc (Zn) - Group 2B = 2+ charge
Cadmium (Cd) - Group 2B = 2+ charge
Atomic mass
amu
Mass of an atom
Based on carbon-12
Average atomic mass
Weighted average of all naturally occurring isotopes of an element
Avg = (amu)(% abundance)+(amu)(% abundance)
Mass spectrometry
Separates particles according to mass
Used to determine masses of atoms & % abundances
1 mole (Avogadro’s number)
6.022 x 10^23 objects
Molar mass
Mass of 1 mole of atoms of an element, expressed in grams
x amu = x g/mol
