Chapter 2 Flashcards
Element
a substance that cannot be broken down to other substances by chemical reactions.
Compound
a substance consisting of two or more elements in a fixed ratio. Has characteristics different from those of its elements.
Atoms are made of subatomic particles:
Proton +
Electron -
Neutron no charge
Isotopes
two atoms of an element that differ in # of neutrons.
Radioactive isotopes:
extra neutrons causes instability and the nucleus decaying turns radioactive. Carbon-14 is unstable which transforms into nitrogen.
Atomic Number
Atomic Mass
Number of protons
protons + neutrons
Valence shell
the outermost shell which contains valence electrons.
First shell: 2
Second third: 8
Full shells are chemically inert, unreactive
Covalent bond
is the sharing of a pair of valence electrons by two atoms. The shared electrons count as a part of each atom’s valence shell. Co-op valences.
molecule
is two or more atoms held by covalent bonds.
Atom
the smallest unit of matter that still retains the properties of an element.
Electronegativity:
an atom’s attraction for the electrons in a covalent bond.
nonpolar
Equally electronegative covalent bonds are nonpolar. SYMMETRICAL
polar
NON equally electronegative bonds are polar. ASYMMETRICAL. WATER
Ionic bond
the attraction between an anion and a cation. The transfer of an electron, one losing one gaining. partial neg/pos charge from transfer.
Cation
Positivley charged ion (lost an electron)
