Chapter 4 Flashcards
Atom
Smallest identifiable unit of an element
Electron
Smaller and lighter than ions, they are negatively charged
Nuclear theory of the atom
Developed by Rutherford; 1) Most of atoms mass and all of its positive charge are contained in the nucleus 2) Volume of the atom is empty space through which the tiny, negatively charged electrons are dispersed 3) There are as many negatively charged electrons outside the nucleus as there are positively charged particles (protons) inside the nucleus, so the atom is electrically neutral.
Nucleus
Contains both positive protons and neutral neutrons
Atomic Mass Unit
Proton Charge: +1 amu
Electron Charge: -1 amu
Neutron: 0 amu
AMU is approximately Protons+Neutrons
Atomic Number
Number of protons in the atom’s nucleus
Periodic Law
Mendeleev; “When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically”
Metals
Left side of periodic table; good conductors of heat and electricity
Nonmetals
Upper right side of periodic table; varied properties
Metalloids (semimetals)
Zigzag line, mixed properties, aka semiconductors (intermediate electrical conductivity which can be controlled and changed)
Main Group Elements
Properties tend to be more predictable based on their position in the table
Transition Elements
Properties are less easily predictable
Family/Group
Each column in the periodic table (Ex: Noble Gases, 8A)
Alkali Metals
1A - Reactive Metals
Alkaline Earth Metals
2A - Reactive, not as much so as Alkali Metals
