Atomic Theory
Described atoms are uncuttable and eternal - atomos
Democritus
What is the difference between an element and a compound
Elements - made of identical atoms
Compounds - made of two or more elements bonded together in definite proportions
What are a column and row on the periodic table called
Column: Group (family)
Row: Period
What is the difference between a pure substance and a mixture
A pure substance cannot be broken down physically. Elements and compounds are chemically bound together in definite proportions.
A mixture can be broken down physically (filtration/distillation). A mixture of substances are not chemically bound together rather they are physically mixed in non-definite proportions
Metalloids
Discovered that multiple elements bond together in whole number ratios to form compounds (Law of Multiple Proportions)
Dalton
What is the difference between an atom and a molecule
Atom: smallest unit of matter
Molecule: made of two or more atoms bonded together in definite proportions
What two things did Mendeleev use to organize the periodic table
Atomic number and physical/chemical properties
What is a valence electron
Electron furthest from nucleus
Order the following elements in increasing atomic number:
Ag, Li, Ge, Rg, I
Li, Ge, Ag, I, Rg
3, 32, 47, 53, 111
What three things are shown an a square of the periodic table
Symbol (letter)
Atomic number (number of protons)
Atomic mass (sum of protons and neutrons)
What is atomic number? Describe its trend as you move up/down and left/right across the periodic table
Atomic number: number of protons
Increase down a column
Increase left to right across a period
Which group is full of non-reactive gases
Noble Gases (Group 18)
Order the following elements in increasing atomic mass:
Cd, Mn, Sc, O, Kr
O, Sc, Mn, Kr, Cd
Discovered the electrons orbit the nucleus in energy levels called orbitals
Atoms of the same element are ____________
Atoms of different elements are ____________
Similar
Different
What is atomic mass? Describe its trend as you move down a column and across a row on the periodic table
Increase down a column
Increase left to right across a row
If elements of the same group react with the same reactant, how will their reactions compare
They will be similar
Remember in our lab: Cl, Br, and I (all group 17) reacted with AgNO3 in the same way while S (group 16) reacted differently
Order the following elements in increasing atomic radius:
Ba, Ca, Au, Cu
Cu, Ca, Au, Ba
What did Shrodinger/Einstein/Heisenberg discover about an electron cloud
Describe the relationship between the properties of elements and compounds. Give an example!
Examples may vary: Diatomic oxygen gas chemically mixes with diatomic hydrogen gas to form a clear neutral liquid (water)
What is atomic radius? Describe the trend as you move down a column and across a row on the periodic table
Atomic radius: distance between nucleus and valence electron
Increase down a group
Decrease left to right across a period
What is Periodic Law
Why does atomic radius decrease as you move left to right across the periodic table
The attraction between the positively charged nucleus and negatively charged electrons becomes stronger, decreasing the atomic radius.
The more protons/electrons you have, the stronger the attraction will be therefore decreasing atomic radius (without adding orbitals)