chemistry of life. composition of matter anything that occupies space and has mass matter is the...
TRANSCRIPT
•Composition of Matter
anything that occupies space and has massMatter
is the quantity of matter an object hasMass
Mass vs. Weight•Weight is determined by the force of gravity acting on a mass
•Example: The same mass would have less weight on the moon than on the Earth
.
90% of the mass of all living things are
composed of just four elements:
Carbon Hydrogen Oxygen Nitrogen
Elements are substances that cannot be broken down chemically into simpler kinds of matter
Elements and Atoms
Over 100 elements exist.
Fewer than 30 are important for
life
•chemical symbol- consists of 1,2,or 3 letters•derived from first letter or other letters in the name •Ex: Chlorine-Cl
•Most other names are derived from Latin names
ELEMENTS – organized in Periodic Table
Consist of 3 SUBATOMIC PARTICLES
•ATOMS – simplest particles of an element that retains all the properties of that element
Protons Neutrons Electrons
nInside Nucleus
Outside Nucleus
NUCLEUS - the central part of an atom and makes up the bulk of the mass of an atom
# electrons = # protons in a NEUTRAL ATOM
high energy –fast orbit very little mass located in orbitals or energy
levels Electrons in outer orbitals have
more energy 1st energy level can only hold 2
electrons 2nd energy level can hold up to
8 electrons
ELECTRONS- are negatively charged particles found orbiting the nucleus of an atom
• shows the kinds and proportions of atoms of each element that forms a particular compound
Chemical Formula
H2O 2 Hydrogen Atoms
1 Oxygen Atom
o Elements will combine to form molecules or compounds if their outer energy level or orbital is NOT FILLED.
o An atom is chemically stable when its highest energy level is filled with the maximum number of electrons. These elements are called noble or inert
elements (gases) and do not react with other elements under normal conditions. (Ex: Helium, Neon)
So,when does bonding occur?
electrons in an atom’s outermost energy level = valence electrons
When outer shell is filled – atom is stable
Hydrogen has ______electron so it needs __________more to fill its first energy level to achieve stability
• Atoms gain or lose electrons to achieve stability• they become either positively charged or negatively charged
• NaCl is table salt and forms from a Na+ ion bonding with a Cl- ion
• Ionic Bonds- form from the attractive force between oppositely charged ions (charged particle)