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)
Anion
a negatively charged ion (gained an electron)
Hydrogen bonds
forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom. Polar. Help molecules stick to each other.
Chemical reactions
The making and breaking of chemical bonds
Dalton
Measurement unit of the mass of protons and neutrons
Matter
Anything that takes up space and has mass
Mass
The amount of matter in an object
