Test Flashcards
Top 4 elements on planet earth
Oxygen, silicon, aluminum, and iron
Top 4 elements in human body
Oxygen, carbon, hydrogen, nitrogen
Dalton so atomicmtheory postulate #1
All matter is composed of indivisible atoms. An atom is an extremely small particle of matter that retains its identity during chemical reactions
•Elements are made of tiny particles called atoms
•Indivisible (no subatomic particles)
Dalton a atomic theory postulate #2
An element is a type of matter composed of only one kind of atoms, each atom of a given kind having the same properties. (mass is one such characteristic property)
•All atoms of a given element are identical
•All atoms of different elements are different
•Law of Conservation of Mass
Dalton so atomic theory postulate 4
Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms
•Subscripts
•A given compound ALWAYS has the same relative numbers and types of atoms
•Law of Constant Composition: fixed proportions
Daltons atomic theory postulate #5
Atoms are indivisible in chemical processes. That is, atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.
•Law of Conservation of Matter
•Atoms rearrange in a reaction
J.j Thompson
Cathode Ray Experiment
•Atoms are NOT indivisible
•Atoms emit tiny negative particles (Proof: electric field repelled)
•Discovered “electrons”
•Calculated the electron mass to charge ratio (not individual value of mass & of charge)
Robert Millikan
Oil Drop Experiment
•Measured the charge on an electron (1.602 X 10 -10 C)
•Used Thomson’s mass/charge ratio and his measured charge value to back calculate the mass of an electron (9.109 x 10-31 kg
Ernest Rutherford
Gold Foil Experiment (alpha particle scattering experiment)
•Most alpha particles pass through foil undeflected, but some are deflected.
•Results:
•Nuclear Model of Atom
•Nucleus: positive charge (Proton)
•Nucleus: dense center around which electrons travel
•Nucleus: accounts for most of the atoms mass
•Most of atom is empty space (visualize: nucleus is size of a grape and electrons are one mile away) nucleus diameter is 10 -13 cm, but atom diameter is 10-8 cm
Rutherford and Chadwick
Neutron: neutral particle
Proof: increased atomic mass
Role: buffer between positive protons and negative electrons (prevents atom from collapsing in itself)
Subatomic particle stats
Mass proton=mass neutron
Electron mass is much much much much much lighter than proton or neutron and doesn’t account for much in weight
- nucleus controls atoms mass
-number of protons determines identity
-electron controls chemical behavior
-neutron is neutral charge
- proton is positive and electron is negative
Isotopes
- Atoms with the same Summer’s of protons but different number of neutrons
- atomic mass is the weighted average of the masses of the available isotopes of an element. The weighing comes from the elements fractional abundance.
Trace elements
Essential to life
●Walsh – studied prisoners (increase Co level decrease violent behavior)
●Trace elements and their function
–Cr helps metabolize sugars
–I proper functioning of thyroid
–Mn maintain proper Ca level in bones
–Cu involved in production of red blood cells
–Li used for treatment of manic depression
Isotope tales Carbon-13/carbon-12 ratio
●Isotopes useful for detective work
– Carbon-13/carbon-12 ratio
●tell if elephant is leaf eater or grass eater
●Diet depends on habitat (living location)
●Identify sources of illegal ivory
Isotope tales Nitrogen-15/Nitrogen-14 ratio
Higher for carnivores than herbivores (carnivores eat more protein via meat)
●Studied this ratio in the wood under King Midas’ casket
●Tells us that King Midas’ diet was rich in meat
