Test 1: Periodic Table, Atoms & Elements Flashcards
Atomic theory
the theory that all matter can be broken down to individual “fundamental pieces” which cannot be divided further
Matter can be divided into two types of pure substances
elements and compounds
Element
Matter that cannot be broken down into smaller substances (made from one type of atom)
The smallest unit of a compounds is a
molecule
Molecule
One or more types of atoms bonded together
4 fundamental assumptions laid out by John Dalton
- All matter is composed of atoms
- The atoms of a given element differ from the atoms of all other elements.
- Compounds are combinations of atoms; each molecule of the same compound has the same number and types of atoms.
- Atoms are not created or destroyed by chemical reactions.
All matter is composed of
Atoms
The atoms of a given element ___ from the atoms of all other elements.
differ
Compounds are
combinations of atoms; each molecule of the same compound has the same number and types of atoms
Atoms are not ___ by chemical reactions.
created or destroyed
Law of Constant Composition
The composition of pure substances always stays the same
Law of Conservation of Mass
Atoms are not created or destroyed by chemical reactions.
Both compounds and elements are considered __ substances
pure
How many known elements exist?
110
Every type of matter or substance on earth comes from
A distinct element or compound
Every element has been assigned a
Name and symbol
Atomic symbol
abbreviations for elements on the periodic table
Compounds contain whole number ratios of
atoms
We represent compounds (multiple elements) by
listing the symbol, followed by the quantity (amount present) of each element
When writing out compounds, parentheses are used to indicate
more than one group of atoms
Atoms are the smallest unit of matter, but they are actually composed of
smaller units with a different charge & mass
Protons
positively charged particles located in an atoms nucleus, along with neutrons
Neutrons
particles with no charge (neutral) that reside in the nucleus with protons.
Electrons
negative charged particles that orbit an atoms nucleus. There are the same number of electrons as there are protons. Have no significant mass (weight).
The identity of an element is defined by the number of
protons in the nucleus
Atomic number (Z)
The identity of an element, which is determined by the number of protons in an atoms nucleus
If an atom somehow lost a proton (it’s identity) it would cease to be
the same element.
If the number of electrons is equal to the number of protons, then the charge is
0 or neutral
If there are more electrons than protons, then the charge is
negative
If there are more protons than electrons, the charge is
positive
protons - electrons =
charge
The strength of the charge depends on
how many more electrons there are of protons, or vice versa
Ion
atom with a charge (unequal proton/electron). An ion is always part of an isotope.
An atom with a charge (ion) means that the protons and electrons are
not equal (neutral)
Cation
An ion with a positive charge
Anion
An ion with a negative charge
We express ions in shorthand notation by
putting the charge in superscript immediately following the atom. ie. P^3- or AI^3+
A change in the number of neutrons an atom has does not
Change the identity or charge.
Protons + Neutrons =
Mass
Atomic mass - Atomic number (protons) =
electrons
Isotopes
Two atoms of the same element with a different number of neutrons (different MASS) All atoms are isotopes, regardless of whether or not they are ions
How do we specify the mass of isotopes in superscript?
in the top left-hand corner of the symbol. ie potassium-39 is ^39K
In a neutral element, there is ___of protons, electrons and neutrons
the same number
The amount of protons never changes, so if we have an isotope (scripted # to the left of element), we
subtract the atomic number (protons) with the isotope mass listed and this will tell us the amount of neutrons. (remember isotope means it is charged and not in a neutral state and will be written in the top left corner of the element name). If it has a charge written to the top right we with add or subtract that from the atomic number to get the amount of electrons present.
the total mass given on the periodic table is a __ average of the masses of each element’s isotopes
weighted
How do we find a weighted average?
(isotope * % of abundance) + (isotope * % of abundance)
The term “period” (periodic table) refers to
horizontal rows of elements which repeat the last line or pattern of reactivity.
The term “group” in the periodic table refers to
vertical columns of elements which are grouped together by properties.
