Science A Flashcards
Dalton
Analogy: “The Billiard Ball”
- Atoms are the smallest particles of matter + are invisible
- All atoms of the same element are identical but differ from other elements
JJ Thompson
Analogy: “The Rasin Bun”
-Atoms had tiny negatively charged particles (electrons)
(Had theories based on electrons, revised the atomic theory)
Rutherford
Analogy: “nuclear”
Stated most of an atom is empty space but contains particles with a positive nucleus and electrons orbit it (gold foil)
(Discovered that atoms has a dense, positively charged core)
Bohr
Analogy: “A solar system”
-colors of light
Electrons existed in a number of energy levels (orbits nucleus)
Neutrons and protons in the middle, electrons orbit
Heisenberg + Schrodinger
Analogy: “The Cloud”
- Not possible to know the path electrons take around nucleus.
- Quantum Theory
- Mathematical
Democritus
- Ancient Greeks started the idea about atoms
- Democritus proposed that all matter was made of particles that could not be divided
- Called them Atomos (meaning invisible)
Who created the periodic table
Dmitri Mendeleev
Groups, Family, Period
Group/Family = vertical column;
-members have similar chemical properties
Period = horizontal row
Elements are classified by metals and non-metals (bold staircase)
Alkali metals, Alkali earth metals, Halogens, Noble gases
AM- Group 1 or first row on the very left (most reactive)
AEM- Group 2
Halogens - Group 17
Noble gases- Group 18 (least reactive)
Properties of metal vs non-metal
Metals- shiny, ductile, malleable, and heat conductors.
Non-metals- dull, brittle, insulators
Atomic # = Protons (Carbon is #6, so Carbon will have 6 protons)
atomic mass is Protons + Neutrons
How to find out how many electrons are in an atom or ion
In an atom, # of protons = # of electrons
In an ion, look at its charge. We know that the atomic # equals the # of protons. Oxygen has a negative charge of 2, so therefore it will have two fewer protons than electrons. (8 protons because of its Atomic# and it’ll have 10 electrons.)
Isotopes
Atoms of an element that differ in a number of neutrons and atomic mass.
Express uranium 238 in isotopic notation form
238 (atomic mass)
U
92 (atomic #)
Ions
an atom that has gained or lost electrons or has a charge, it is an ion.
If an element loses one or more electrons to become a positively charged ion, it is called a cation.
Elements that gain electrons to become ions are known as anions.
How many electron rings would magnesium have?
3 because its found in period 3