chap 2 Flashcards
define atom
structural unit of element. smallest form that retains physical/chemical properties of that element
what are the three main parts of atom?
electrons, protons, and neutrons
define nucleus
small dense region in the center of atom. positively charged and contains nearly all the mass of an atom but is only 1/10000 volume of atom
define nuclide symbol
specific atom with unique number of protons and neutrons
A +/-
X
Z.
what does each mean?
X- element symbol
A-mass # =
protons+neutrons(defines isotope of element)
Z-atomic #= # of protons. defines the element(if you change protons you change element)
+/- indicates the charge due to diff # of electrons=ION
define isotope
variant of an element where atoms have the same number of protons (atomic number) but a different number of neutrons. resulting in different atomic masses while still maintaining the same chemical properties(only effects mass)
define ion
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
what did JJ Thompson do/discover?
used cathode ray tube(beam of light with atom. has postitive and negative magnet on either side) saw that beam went towards the postive magnet therefore electrons must exist. alr knew atom had p+ and n.
what did robert millikan do/discover?
did oil drop experiment where charged oil droplets are balanced between gravity and electric fields. oil is atomized by atomizer over (+)plate then falls and forms line over (-)plate discovered the charge of a single electron
what is the plum pudding model and who came up with it?
jj thompson. circle(pudding) is positivly charged then little electrons (plum) distributed throughout.
what was the gold foil experiment and who create?
ernest rutherford. took very very thin gold foil(few atoms thick) and used emitter to beam particles through foil. found that particles being emitted through sometimes bounced back meaning atom must be mostly empty space except NUCLEUS cause electrons not big enough to make particle bounce back only stray
what was the rutherford model +looks ?
says that there was a positivly charged nucleus that takes up most mass but barely any space and electrons just reside around it. looks like science symbol
who came up with the periodic law and periodic table?
Dmitri mendeleev and lothar meyer
how did mendeleev think of the periodic table +looks?
was 60 known elements at the time(didnt know about p,n,e) mendeleev recognized patterns of elements and found things that were supposed to be there but werwnt discovered yet so made placeholders based on predictions of physical and chemical properties. columns and rows ?-placeholder
what did mendeleev observe about elements?
physical properties-malleable,ductile-stretch into wire,shiny,brittle,luster,melting/boiling pts,density
chemical properties-combining properties N+H 1:3-ammonia
reactivity- Li,Na,K diff masses but react violently with water
trends and repeated patterns- Os,Ir,Pt similar mass and characteristics
label parts of periodic table(groups and individual)
Main group:
first column-alkali metals
second column-alkaline earth metals
16th column-chalcogens
17 column- halogens
18 column- inert/noble gases
metalloids-B,Si,Ge,As,Sb,Te,Po
nonmetals-right above and H metalloids
metals-include transition, left main group, below metalloid, inner transition
inner transition-two seperate rows
transition- middle section
define metals
conduct heat,electricity, malleable, ductile, shiny, solid at room temp generally
define nonmetals
most gases at room temp or brittle solid or liquid
ions have two types called?
+=cation
-=anion
what is avogadros number?
6.022 x 10^23
define avogadros law
under the same conditions of temperature and pressure, equal volumes of different gases contain an equal number of molecules
define mol
unit fpr calculations of mass of molecules (mass in grams of 1mol(g/mol))
