Download 2.2 LIFE REQUIRES ABOUT 25 CHEMICAL ELEMENTS

2.2 LIFE REQUIRES ABOUT 25
CHEMICAL ELEMENTS
WHAT IS A CHEMICAL ELEMENT?
A chemical element is a substance that cannot be broken
down to other substances by ordinary chemical means
There are 92 naturally occurring elements
About 25 elements are essential to life
NAME THE BIG FOUR HUMAN ELEMENTS.
oxygen (65% of human body by weight)
carbon (18.5%)
hydrogen (9.5%)
nitrogen (3.3%)
WHAT ARE TRACE ELEMENTS AND WHY ARE
THEY IMPORTANT?
a trace element is an essential element to most organisms, but
only in minute quantities (humans need .15 mg of iodine vs
1000 mg of calcium daily)
they are important for proper function of an organism
(often as catalysts or enzyme cofactors)
GOITERS
So you think you are having a bad day.
WHAT CAUSES GOITERS?
Goiters are caused by an
iodine deficiency
iodized salt takes care of
this problem in most
countries
2.3 ELEMENTS CAN COMBINE TO
FORM COMPOUNDS
HOW DO YOU FORM A COMPOUND?
Two or more chemical elements combined in a fixed ratio of
atoms form compounds
HOW IS TABLE SALT MADE?
sodium (Na) + chlorine (Cl) → sodium chloride (NaCl)
Salt Crystals
2.4 ATOMS CONSIST OF PROTONS,
NEUTRONS, AND ELECTRONS
NAME THE THREE COMPONENTS OF AN
ATOM.
An atom is made up of protons and neutrons which are
located in a central nucleus
The nucleus is surrounded by electrons
WHAT HOLDS THE PARTS OF AN ATOM
TOGETHER?
Each atom is held together by attractions between the
positively charged protons and negatively charged electrons
Neutrons are electrically neutral
2
6
Protons
Nucleus
2
Neutrons
2
Electrons
Helium atom
Protons
6
Neutrons
6
Electrons
Nucleus
Carbon atom
ALL ATOMS OF AN ELEMENT HAVE THE SAME
NUMBER OF...
Protons
WHO IS THE DEBBIE DOWNER OF SUBATOMIC
PARTICLES?
Electrons are negatively charged.
William Q after a Charger loss
WHAT IS THE DIFFERENCE BETWEEN ATOMIC
NUMBER, ATOMIC MASS, AND ATOMIC
WEIGHT?
Atomic number is the number of
protons in an atom.
Atomic mass and atomic weight
refers to the number of protons and
neutrons in an atom.
WHAT EXAMPLE OF A COMPOUND IN YOUR
BODY WAS USED IN THE BOOK?
the protein actin
Which protein works with actin to make your muscles
move?
myosin and actin make up a myofibril, which is the organelle
found in muscle cells responsible for movement
WHAT IS AN ISOTOPE?
atoms with the same atomic number but different atomic
mass
Some isotopes are unstable and radioactive
HOMEWORK:
Packet Exercise 3
Read Sections 2.5 and 2.6
Radioactive