Ch.2: Chemistry Flashcards
anything that takes up space and has mass
matter
a substance consisting of two or more elements in a fixed ratio
Compound
a substance that cannot be broken down
element
About ___ of the 92 elements are essential to life
25
What four elements make up 96% of living matter
Carbon, hydrogen, oxygen, and nitrogen
those required by an organism in minute quantities
Trace elements
Most of the remaining 4% consists of
calcium, phosphorous, sulfur, and potassium
s the number of protons in its nucleus
atomic number
the atom’s total mass, can be approximated by the mass number
atomic mass
the sum of protons plus neutrons in the nucleus
mass number
are those in the outermost shell,
Valence electrons
Elements with a full valence shell are chemically XXX. They don’t want to gain or lose any electrons
inert
Interactions of valence electrons usually result in atoms staying close together, held by attractions called
Chemical bond
A XXXXXXXX is the sharing of a pair of valence electrons by two atoms
In a covalent bond, the shared electrons count as part of each atom’s valence shell
covalent bonds
The notation used to represent atoms and bonding is called a XXXXXX
For example, H–H
Structural formula
This can be abbreviated further with a XXXXX
For example, H2
Molecular Formula
an atom’s attraction for the electrons in a covalent bond
Electronegativity
the atoms share the electron equally
non polar covalent bond
one atom is more electronegative, and the atoms do not share the electron equally
Polar covalent bond
Atoms sometimes strip electrons from their bonding partners
An example is the transfer of an electron from sodium to chlorine
After the transfer of an electron, both atoms have charges
Ionic bond
A charged atom (or molecule) is called an
ionic bond
is a positively charged ion
cation
is a negatively charged ion
anion
forms when a hydrogen atom bonded to one atom is also attracted to another
Water molecules are attracted to one another via H bonds.
hydrogen bonds
Biological molecules recognize and interact with each other with a specificity based on
Molecular shape
are the making and breaking of chemical bonds
chemical reactions
6 CO2 + 6 H20 → C6H12O6 + 6 O2
carbon dioxide + water > glucose + oxygen
