2.1- The Nature of Matter Flashcards
What is an Atom?
Subatomic particles that make up an atom:
the basic unit of matter
protons, neutrons, electrons
What is the nucleus?
the center of an atom that contains positivley charged protons, and neutrons with no charge
What are electrons?
negativley charged particles with almost no mass, and are in constant motion in the space surrounding the nucleus
Atoms have an ———– so they are neutral
equal number of electrons and protons
What is an element?
a pure substance that is entirely one type of atom
How are the elements orgainzed?
By atomic number (the number of protons each atom has)
What are isotopes
atoms of the same element that have a differnet number of neutrons
What is atomic mass number?
the total number of protons and neutrons in the nucleus
Radioactive isotopes are both:
extremly dangerous but helpful
What is a compound?
a substance formed by the chemical combination of 2 or more elements in definite proportions
A chemical formula:
shows the compostion of compounds
Ex: NaCl (table salt)
Physical and chemical properties of compounds are:
Example:
very differnet from the elements that form them
Chlorine is very reactive but forms sodium chloride which essentail for
Chemical Bonds:
hold atoms in compounds together
bond formation involves valence electrons (electrons in the outer shell)
What is an ionic bond?
When 1 or more electrons are transferred from one atom to another, resulting in ions that attract to each other becuase of their opposite charges
What is an ion?
when an atom loses or gains electrons and becomes positively or negatively charged