Section 2: Modern Periodic Table Flashcards
Did Mendeleev know about protons
No, he developed his table before they were discovered
How are elements arranged in the modern periodic table
Increasing atomic number
Period
Each row in the table of elements
Why does the number if elements per period vary
The number of available orbitals increases from energy level to energy level
Group
Each column in the table
What do elements in groups have in common
Similar electron configurations, chemical properties, valence electrons
When do properties of elements repeat in a predictable way
When atomic elements are used to arrange elements into groups
Periodic law
Pattern of repeating qualities
Atomic mass
A value that depends on the distribution of an element’s isotopes in nature and the masses of those isotopes
Atomic mass unit
Defined as 1/12 the mass of a carbon 12 atom
Why do we have amu
The mass of an atom is extremely small
Weighted average
Some values are more important than others
How is Atomic Mass found
(Mass Number • Percentage) +
Mass Number • Percentage
What are elements classified as
State at room temperature, occurrence in nature, and general properties (metals nonmetals metalloids)
Metal qualities
Conductors of electric heat and current, mostly solids at room temp, malleable, ductile, varying reactivity
Transition metals
Elements that form a bridge between the elements on the left and right sides of the table, among first to be discovered, ability to form compounds with distinctive colors
Nonmetals
Poor conductors. Low boiling points, mostly gases, brittle, varying reactivity
Metalloids
Properties between metals and nonmetals. Ability to conduct heat varies with temp.
Across a period from left to right (how metallic)
Less metallic and more nonmetallic
Is it wise to hold sodium in ur hand
No, that would be imprudent.
Where are the most reactive metals
Left side
