Wang H Chem Quiz 2.4-2.6

**make sure to know how to find the average atomic mass + percent abundance from 2.5**

Subatomic particles

the smaller particles in an atom

Nucleus

positively charged; dense core in the center of atom; contains 99.9% mass of atom; takes up very little space; houses protons and neutrons

Electron Cloud

takes up most space of atom

Energy shells

electrons found in area of higher probability

Protons

symbol p+; charge +1; 1 amu

Neutrons

symbol n0; charge 0; 1 amu

Electrons

symbol e-; charge -1; ~ 0amu

Atomic mass unit (amu)

same as molar mass (g/mole)

Atomic number (Z)

the number of protons in an atom; all atoms of the same element have the same this; same as number of electrons in neutral atom

Atomic mass (A)

number of protons + neutrons; unit g/mole; A = Z + N

Ions

charged atoms due to losing/gaining e- from outer shell

Cation

positively charged ion

Anion

negatively charged ion

Valence Electrons

the electrons in the outermost shell; the ones that do the chemical bonding

Charge of an ion when it loses an electron?

positive

Charge of an ion when it gains an electron?

negative

Isotopes

atoms of the same element w/different number of neutrons + have different mass mass number; name of it is written as: element name - atomic mass (like Carbon-12)

Most elements exist as ____________ in nature

mixture of isotopes

Radioactivity

the ability of substance spontaneously emit high-energy radiation

Radioactive isotopes

a lot of unstable isotopes of elements are radioactive

Alpha particle

charge +2 (Helium) and 4 amu

Belta particle

charge -1; 0amu

Gamma

charge 0; 0 amu

Mass of each proton/neutron

1 amu

Average atomic mass

on periodic table; NOT a whole number, but each isotope's mass is a whole number; weighted average

Formula for calculating average atomic mass

mass isotope A(%A) + mass isotope B(%B) + ...

Mendeleev

ordered elements by atomic mass + saw a repeating pattern' put elements w/similar chemical properties in same column

Periodic Law

when the elements are arranged in order of increasing atomic number, certain sets of properties recur periodically

Periodic Table

elements arranged by atomic number; neutral atoms are arranged w/similar properties (physical + chemical) in same column

Column

groups

Rows

periods

Main Group/Representative Elements

elements in 'A' group

Transition Elements/Metals

elements in 'B' group

Inner Transition Metals/Rare Earth Elements

elements in bottom 2 rows (technically in periods 6 + 7)

Major divisions of elements

metal, metalloid, + nonmetal

Metals

all are solid at room temperature, except Hg (mercury); its atoms LOSE electrons in reactions to be cation

Nonmetals

found in all 3 states of matter; its atoms GAIN electrons to be anion in ionic compounds

Metalloid

show properties of both metals + nonmetals; aka semiconductors

Hydrogen

nonmetal; pure form is a gas (diatomic gas; H2)

Acid

special kind of molecular compound; formed between H + nonmetal

Group 1A

Alkali Metals; doesn't include H; very reactive + never found uncombined in nature; react w/water to form basic solutions (hydroxide) and H2 gas

Group 2A

Alkali Earth Metals or Alkaline Metals ⇾ harder + less reactive than corresponding alkali metals; only Ca, Sr, Br (CBS) reaction w/water to form basic hydroxides

Group 7A

Halogens; nonmetals; all diatomic pure elements (like F2 is the pure element of F); exist in 3 states of matter; F2 and Cl2 are gasses; Br2 is liquid; I2 and At2 are solids; react w/metals to form ionic compounds; react w/H to form acids

Group 8A

noble gasses; all gasses at room temperature; very unreactive + practically do NOT react w/anyone