Atoms & Their
Interactions
Chapter 6.1
Elements
• Elements are substances that cannot be broken
down into simpler chemical substances
– Made of only one kind of atom
– Example: gold
• 90 elements occur naturally
– 25 elements are essential to living things
– Carbon, hydrogen, oxygen, and nitrogen make up 96%
of a person’s mass.
• Trace elements = found in small amounts
– Required for healthy cells
– Examples: iron & magnesium
The
Periodic
Table
• Elements are represented by a symbol in
the periodic table
– Carbon = C; Hydrogen = H; Oxygen = O
• Element symbols are from the Latin root
name for the element
– Fe (Ferous)= Iron, Au = gold, Ag = silver
Atoms
• Smallest particle with the characteristics of an
•
element
Made of protons (+), neutrons, and electrons (-)
– Nucleus = protons & neutrons
– Electrons form a cloud around the nucleus
• Atomic # = the number of protons
Ions & Isotopes
• Isotopes = element with a different number of
neutrons
– Example: carbon 13 & carbon 14 used for carbon
dating
• Ions = atoms that have gained or lost an
electron
Compounds
• Compounds are anything made up of more
than one type of atom
– Most materials are compounds
– Examples: water, carbon dioxide, salt
• Compounds form so atoms are more stable
– Neutral charge
– 8 e- in outer shell
Covalent Bonds
• Two atoms share
electrons to form a
molecule
• Attraction between the
nucleus & electrons
holds the atoms
together.
• Examples: Water,
Carbon Dioxide
Ionic Bonds
• Strong attraction between ions of opposite
charge
– Electrons are given or taken by another
– Form ionic compounds
– Example: salt (NaCl)
Chemical reactions
• Bonds between atoms are formed or broken to
•
form different molecules
Metabolism = all of the chemical reactions that
occur in an organism
– In organisms, chemical reactions occur in cells
– Metabolic reactions break down molecules &
compounds needed by the body
Example:
2H2 + O2  2H2O
Mixtures & Solutions
• Mixture = individual parts
retain their own properties
– Example = sand + sugar
• Solution = One substance is
dissolved in another
– Solvent (liquid) + solute (solid)
– Example: Kool-aid
Acids & Bases
• Chemical reactions in the body often
depend on pH
– pH = a measure of how acidic or basic a
substance is
• Acids have a pH of 0 – 7
– Form H+ ions when put into water
• Bases have a pH of 7 – 14
– Form OH- ions when put into water
Review
• What elements are most abundant in the body?
– Carbon, hydrogen, oxygen, and nitrogen
• What is the nucleus of an atom made of?
– Protons & neutrons
• Why do atoms form compounds?
– To become more stable
• How are ionic and covalent bonds different?
– Covalent = share electrons, ionic = give or take an electron
• What is metabolism?
– All of the chemical reactions in a living organism
• How are mixtures & solutions different?
– the elements that make up a mixture retain their individual
properties.
• A solution with a pH of 2 would be a(n)
– ACID
Video: Elements of Chemistry
• Title Your paper
• Number from 1-10, skipping one line
between each number
• Write down 10 facts from the video.