Chapter 2 Flashcards
Atoms, Molecules, Ions
What led to and who developed the Atomic Theory of Matter?
laws of constant composition, conservation of mass, and multiple proportions led to the theory, John Dalton developed it
What is the Law of Conservation of Mass?
the total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place
What are the Postulates of Dalton’s Atomic Theory?
1) each element is composed of extremely small particles called atoms
2) all atoms of a given element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of all other elements
3) atoms of an element are not changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions
4) atoms of more than one element combine to form compounds; a given compound always has the same relative number and kind of atoms
What are the subatomic particles, their charges, their masses, and their locations in the atom?
protons +1 charge, relative mass 1
electrons -1 charge, relative mass 0
neutrons 0 charge, relative mass 1
protons and neutrons in nucleus, electrons travel around the nucleus
What is the atomic number?
number of protons in the nucleus of an atom; whole number on the table; #protons=#electrons because atoms have no overall charge (elements in their elemental form have 0 charge); atomic number written as a subscript BEFORE the symbol
What is the mass number?
total number of protons and neutrons in the nucleus of an atom; written as a superscript BEFORE the symbol
What are isotopes?
atoms of the same element with different masses; have different number of neutrons, but the same number of protons
What is the base unit for mass on the atomic level?
amu, atomic mass unit
1 amu = 1.66054x10^-24 g
What is atomic weight?
an AVERAGE mass found using all isotopes of an element weighted by their relative abundances
Some things about the periodic table?
- elements are arranged in order of atomic number
- rows are called periods (7)
- columns are called groups (18)
- elements in the same group have similar chemical properties
What are some of the different groups in the periodic table?
group 1 - (except H) alkali metals
group 2 - alkaline earth metals
group 3 - oxygen group
group 17 - halogens
group 18 - noble gases (don’t interact with the “commoners”)
Where are metals on the periodic table and what are some of their properties?
on the left side of the periodic table; properties: shiny/have luster, good heat conductor, good electricity conductor, malleable (can form by hitting with a hammer), ductile (can be pulled into a wire), form cations (positive ions)
Where are nonmetals on the periodic table and what are some of their properties?
on the right triangle of the periodic table and hydrogen; properties: dull color/colorless, brittle in solid form, poor heat conductor, poor electricity conductor, form anions (negative ions)
Where are metalloids/semi-metals on the periodic table?
in between metals and nonmetals (diagonal, stair step, stair step, stair step); properties not easily predictable
What does the subscript to the right of the symbol of an element tell you?
the number of atoms of that element in one molecule of the compound
