Lecture 2 Flashcards
How many naturally occurring elements are there
92
Compounds and elements are ________ Substances
Pure
True or false; Pure substances can be separated into smaller parts by physical means
False, cannot
True or false; Solutions and mixtures are able to be separated into smaller parts?
True
True or false; Elements can be separated by chemical reactions
False
True or false; Atoms are the largest unit of chemical matter
False, smaller
An allotrope is
An element that has more than on stable form ,
ex; oxygen, o2 and o3
Protons are located where
in the nucleus
Electrons are located where
they orbit a molecule
Neutrons are located where
The nucleus
Neutrons weigh the sane as _____ but have ___ charge
Protons, no charge
Isotopes are
when an element can have different numbers of neutrons
ex; Hydrogen, 1H, 2H, 3H
What makes the atomic weight of an element
the number of protons plus neutrons
Unpolluted dry air at sea level and standard pressure contains what three major constitutes and what 5 minor gases
major: Nitrogen, oxygen, argone
Minor: Carbon dioxide, Ne, Helium, CH4, N2O3
Most environmental issues result from change in the __________ gases
minor
