Physical Science Flashcards
Chemistry
the study of elements and the compounds
they form. Matter can take the form of an element, a
compound, or a mixture.
Element
the basic form of matter, incapable
of being decomposed by chemical means into simpler
substances. Each element has distinct chemical and
physical characteristics. Hydrogen (H), oxygen (O),
and carbon (C) are elements.
Compound
a combination of two or more
elements chemically combined in a specific proportion.
Compounds can be separated by chemical means,
and are represented by chemical formulas that include
the symbols of all the elements present. Examples of
familiar compounds are water (H2O) and table salt
(NaCl). In order to be considered organic, a compound
must contain carbon.
Mixture
a combination of two or more substances
that are not chemically combined. Dissolving
salt in water results in a mixture. The two compounds
don’t react with each other and can be separated by
physical means—in this case, heating the water so it
evaporates, leaving the salt behind.
Atom
the smallest unit of an element that retains
all of the element’s chemical properties. An atom
is composed of three primary particles: electrons,
protons, and neutrons.
Electron
found outside the nucleus (the center of
an atom), it has a negligible mass and a charge
of –1.
Proton
found in the nucleus, it has a mass of 1
amu (atomic mass unit) and a charge of +1.
Neutron
found in the nucleus, it has a mass of 1
amu and no charge.
Atomic number
the number of protons in the atom. The atomic number determines the element.
Mass number
the total number of protons and
neutrons in one atom of an element. Mass number
can vary because the number of neutrons in an atom
can change.
Solid
Retains a fixed volume and shape
- Not easily compressible
- Does not flow easily
Liquid
Assumes the shape of the part of the container which it occupies
- Not easily compressible
- Flows easily
Gas
- Assumes the shape and volume of its container
- Compressible
- Flows easily
Combined Gas Law
According to the law, if volume remains constant,
pressure will change in proportion to temperature.
Dalton Model
1803 John Dalton proposed an “atomic theory” with spherical solid atoms based upon measurable properties of mass. “Solid Sphere Model”
Thomson Model
1898 JJ Thomson used a CRT to experimentally determine the charge to mass ratio of an electron. “Plum Pudding Model” / Electrons
Rutherford Model
•1911 Rutherford Nucleus is dense, small, and positively charged. Electrons are located outside the nucleus. “Planetary Model” / Nucleus