Chap 2 Powerpoint Flashcards
The atom describes the smallest part of the four substances of matter, which are:
Earth, water, fire, air
Atom- what language is it derived from and what does it mean?
Greek and “indivisible.”
The atoms is the smallest…
…unit of matter.
Matter is…
…a mixture of substances.
A substance is…
…material that has definite and constant composition.
A mixture is:
Two or more substances (not chemically combined.)
An element is:
A simple substance.
A compound is:
A complex substance.
The atom is the smallest particle of matter that has the properties of:
An element.
How many naturally occurring elements are there?
92.
How many known elements?
103
The Periodic table of elements is:
An arrangement of elements in order of increasing atomic mass in which a periodic repetition of similar chemical properties occur.
How are elements in the same group similar and how is their placement in a particular group determined?
Elements within the same group chemically react in a similar fashion and have similar physical properties. Their grouping is determined by the placement of electrons in each atom.
Who discovered electrons and when?
JJ Thomson (while studying properties of cathode rays) in 1890.
Who discovered that the nucleus is positively charged and surrounded by negatively charged electrons and when?
Ernest Rutherford in 1911.
Describe Bohr’s model (when was it developed?)
Resembles a mini solar system, contains a small, dense, positively charged nucleus surrounded by negatively charged electrons theta revolve in fixed, well-defined orbit about the nucleus. (1913)
What are the fundamental particles of an atom?
the electron, the proton, and the neutron.
What are the nucleons of an atom?
the proton and neutron.
What is equal in the neutral atom?
the number of electrons is equal to the number of protons in the nucleus.
What is the main difference between protons and neutrons?
Electric charge (protons are positively charged and neutrons are neutral.)
The atom is in a constant vibrating motion due to:
the strong positive nuclear force field which is surrounded by negatively charged spinning and orbiting electrons.
