Transcript Chemistry Vocabulary PowerPoint

BASIC CHEMISTRY
DEFINITIONS
1) Matter
anything that occupies space and has mass.
(also inertia- resisitance to a change in motion)
Total Shuttle Mass 2,029,203 KG (4,474,574 LB)
= 2,237.287 tons
2) Element
• - a pure substance that consists entirely of one
kind of atom. They are represented on the
periodic table of elements with 1-2 letters such a
H for hydrogen, and Na for Sodium.
3) Atom
It means “unable to cut…”
It is the basic unit of matter (simplest part of an
element that retains the properties of that
element.)
Current Atomic Theory
• The atom consists of a small, dense
positively-charged nucleus surrounded by
mostly empty space. (Most of the atom’s
volume is empty space.)
• If the nucleus was the size of an orange,
the whole atom would measure about 24
city blocks.
• If the nucleus was the size of a small
paper clip, the whole atom would be the
size of a football stadium.
• Even though the atom’s nucleus is
relatively small, it makes up over 99.9% of
the atom’s mass.
4) nucleus
(of an atom, not of a cell) – the center of
the atom that contains the protons and
the neutrons or subatomic particles
5) protons
positive particle in
the nucleus
6) neutron
the neutral (no charge)
particle in the nucleus
7) electrons
the negative particle that moves around the
nucleus, (Electrons are of negligible mass
compared to the protons and neutrons.)
To Find The Number of Protons,
Neutrons & Electrons
The atomic number gives you: the number of
protons ,
as well as electrons
For boron:
5 protons,
5 electrons
• The atomic mass give you:
the sum of the protons + neutrons
To find the number of neutrons: subtract the atomic
number from the atomic mass. (round atomic mass
first) For boron: 11 – 5 = 6
Isotope
Atoms (elements) with the same atomic number
that have different numbers of neutrons. (for
example: Carbon 12, Carbon 13, & Carbon 14,
or Hydrogen 1, 2, & 3). Some are radioactive.
C-12
C-14
8) compound
a pure substance that is made
up of the atoms of two or more elements,
chemically combined in definite proportions.
It may be represented by a chemical formula,
such as:
H 2O
or
NaCl,
or
CO2.
9) Chemical reaction
The process by which compounds are
formed or broken down. Most elements
tend to undergo chemical reactions to make
their atoms more stable. Bonds are broken
and formed, and atoms are rearranged.
Substances formed have different
properties than the original substances.
• Outer shell electrons called valance
electrons are involved in chemical bonding.
• Atoms are more stable what they have 8
(sometimes 2) valance electrons in their
outer shell. – This is called the octet rule.
10) Covalent bond
Two atoms share one or more pairs of electrons.
formed when electrons are shared between
atoms in a compound.
The structure formed is called a molecule and is
the smallest part of a covalent compound.
(A water molecule is covalently bonded.)
11) Molecule
- simplest part of a substance (covalently-bonded
compound) that retains the properties of the
substance. (Made up of two or more different
elements chemically combined.)
12) Ionic bond
a chemical bond between atoms in which one
or more electrons are transferred.
13) ions
The atoms involved in an ionic bond become
charged during the chemical reaction. They are
called ions (+ ions lost, while – ions gain
electron/s) Negative ions are attracted and bond
to positive ions.
NaCl (Salt) = Na+ and Cl-
14) States of matter
Solids, liquids, gases- states of matter
determined by the rate at which atoms or
molecules move.
• Solids- tightly packed with fixed
volume & shape,
• Liquids – not as tightly, linked
with fixed volume, but not shape.
• Gases- particle with little or no
attraction-no fixed volume or shape.
15) Reactants and products
Reactants – left side of the chemical
equation, while the right side = Products.
16) mixture
matter composed of two or more elements, or
compounds, that are physically mixed together,
but not chemically combined. Salt and pepper
stirred together is a mixture.
17) solution
(homogenous)
• a mixture of two or more substances in
which the molecules of the substances are
evenly distributed. (salt dissolved in water)
Solutions can be mixtures
of liquids, solids, or gases.
solution, solute & solvent
A solution is a mixture in which a solute is
dissolved in a solvent. It has very small
particle size. (homogenous mixture.)
Salt water
solute -substance dissolved to form a
solution (salt - NaCl),
solvent – substance in which a solute is
dissolved (water – H2O)
COLLOIDS:
• Particles that are intermediate in size between those
in a solution or a suspension from heterogeneous
mixtures called colloidal dispersions or simply
colloids. Particles of a colloid are small enough to
stay suspended by the constant movement of
surrounding molecules.
• Colloidal particles make up a dispersed phase, while the
solvent-like phase is called the dispersing medium.
Examples: Gels, emulsions, foams, aerosols, fog, smog, etc.
Cytoplasm is said
to be a colloidal
dispersion.
SUSPENSIONS:
• A mixture of water and undissolved
materials. The particles larger than those
in solutions or colloids, but are small
enough so that they don’t settle out, or are
suspended for a time by the movement of
the water. If the water stops moving, they
tend to settle-out.
18) acid
Solution with higher concentration of H+ ions
(also hydronium ions) than pure water.
Strong acids tend to have pH values that are
low & range from 0-3. (lower OH- hydroxide
ions)
Hydrochloric Acid in water
• Acids tend to be sour, and in
concentrated forms, highly
corrosive to some materials.
• Your stomach contains
hydrochloric acids which
makes vomiting irritating
to tissues.
• Sulfuric acids is found
in car batteries and used
in many manufacturing
processes.
• Penny tarnish can be
removed with the acids in catsup.
HYDRONIUM IONS
Water itself can dissociate into two ions of
opposite charge.
Pure water contains equal numbers of
hydronium (H3O+) and hydroxide ions (OH-)
in solution.
19) base
A solution with lower concentration of H+ ions
(hydronium H3O+) than water (higher OHhydroxide ions) These solutions are said to be
alkaline. Strong bases tend to have pH values
from 11 – 14.
Sodium Hydroxide in Water
Bases tend to taste bitter.
Basic solutions are called alkaline.
Bases feel slippery. They can react with the
oils in the skin to form soap. Soap can be
made by reacting fat with a base.
Early soap-making with lye and animal
fat. It is called saponification.
Bases can be caustic.
Sodium hydroxide is also called “caustic
soda” and can cause chemical burns.
20) pH scale
a scale to measure the concentration of H+ ions
(hydrogen ions or hydronium ions) in solution.
pH Numbers
Acid – Base indicators
• Chemical Indicators: substances such as
litmus paper can be used to detect the presence
of an acid or base. They can also approximate
pH number.
An Electrolyte Tester
Electrolytes have ions in solution. These
allow the electric current to flow. This can
be demonstrated by an electrolyte tester.
HCl dissolved in water
released ions into the
water that can conduct
an electric current.
Acid, base, or salt solutions are
electrolytes
ELECTROLYTE: any substance containing
free ions that make the substance electrically
conductive. (The most typical electrolyte is an
ionic solution, but molten electrolytes and solid
electrolytes are also possible.)
21) buffers
weak acids or bases that can react with
strong acids or bases to prevent sharp,
sudden changes in pH.