Grade 8 Science - Chapter 3 and 4 - Atoms and the Periodic Table
Atomic structure, atomic masses, the periodic table, families of the periodic table
Terms in this set (37)
The atom is the smallest particle that has the properties of an element. The atom is the basic building block of matter. An atom has NO CHARGE. The word atom comes from the Greek word "atmos" meaning "unable to be divided"
A substance that cannot be broken down into simpler substances.
A subatomic particle. A proton is found in the nucleus of an atom. A proton has a POSITIVE CHARGE.
A subatomic particle. A neutron is found in the nucleus of an atom. A neutron has NO CHARGE (it is "neutral".)
Neutron (0 charge)
A subatomic particle. An electron is found outside the nucleus of an atom. An electron "orbits" the nucleus of an atom in an "electron cloud". The electron has a NEGATIVE CHARGE.
NUCLEUS of an ATOM
The center of an atom; it is made up of PROTONS and NEUTRONS.
The number of PROTONS in the nucleus of an atom. In an atom, the number of protons is equal to the number of electrons.
#protons = #electrons
The region in an atom where electrons are found. Orbitals are the "energy levels",.a region in an atom where there is a high probability of finding electrons
Refer to Bohr's model...each electron has a certain energy that is determined by its path around the nucleus. Electrons GAIN ENERGY to move to a HIGHER LEVEL or LOSE ENERGY to move to a LOWER LEVEL.
ATOMIC MASS NUMBER
The total number of PROTONS + NEUTRONS in the nucleus of an atom. Most of the atom's mass is in the nucleus.
Mass number = #protons + #neutrons.
For example, an atom with 6 protons and 6 neutrons will have at atomic mass of 12 amu (atomic mass unit).
The Sub-Atomic Particles
Protons, neutrons and electrons.
relative mass relative charge
proton 1 +1
neutron 1 0
electron 1/1836 -1
AVERAGE ATOMIC MASS
The weighted average of the masses of all naturally occurring isotopes of an element.
1913...Bohr suggested that electrons in an atom move in set paths around the nucleus much like the planets orbit the sun in our solar system.
What is an atom's charge?
An atom has no charge because it has an equal number of protons (+) and electrons (-)
What is the charge for an atom's nucleus?
The nucleus of an atom has a positive charge
An atom or group of atoms that has lost or gained one or more electrons
The gaining or losing of electrons in order for an element to fill its outermost energy level.
An ion with a negative (-) charge. The atom has GAINED electron(s)
An ion with a positive (+) charge. The atom has LOST electron(s)
Atoms having the same number of protons but different numbers of neutrons
The periodic table groups similar elements together. This organization makes it easier to predict the properties of an element based on where it is in the periodic table.
A Russian chemist. He is credited as being the primary creator of the first version of the periodic table of elements. Though there were other contributors to the table, Mendeleev predicted the properties of elements yet to be discovered.
GROUP (or family)
The vertical column of elements on a periodic table. Elements in the same group have the same number of valence electrons. Elements in the same group have similar properties. (also known as a "FAMILY"
PERIOD (or row)
A horizontal row of elements in the periodic table.
AVERAGE MASS UNIT "AMU"
A quantity equal to 1/12 of the mass of a carbon-12 atom
An electron in the OUTERMOST energy level of an atom
Group I on the periodic table. One valence electron that is easily removed to form a POSITIVE IONS. Highly reactive.
ALKALINE EARTH METALS
Group II. TWO valence electrons. Less reactive than alkali metals,.
Located in 3-12 of the periodic table.
Group 17. Highly reactive. Form NEGATIVE IONS
Group 18. Non-reactive. Exist as atoms instead of molecules. DO NOT form compounds with other elements under normal circumstances (they are "Inert").
SEMICONDUCTORS (also called Metalloids)
Boron, silicon, germanium, arsenic, antimony and tellerium. Has properties of metals and nonmetals and can conduct electricity if electrons manipulated
Located on the left side of the periodic table. Metals are shiny solids that can be stretched and shaped (malleable), good conductors of heat and electricity
Located on the right side of the periodic table. Nonmetals may be solids, liquids, or gases. Solid nonmetals are dull and brittle and are poor conductors of heat and electricity (but mome elements labeled as nonmetals can conduct under certain conditions.
METALLOIDS (also called Semiconductors)
Also called "semiconductors". Intermediate conductors of heat and electricity
DALTON'S ATOMIC THEORY
1. Every element is made of tiny, unique particles called atoms that cannot be subdivided
2. Atoms of the same element are exactly alike
3. Atoms of different elements can join to form molecules
The smallest unit of a substance that exhibits all the properties characteristic of that substance. Made up of 2 or more atoms
A substance made of atoms of more than one element bound together
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