CHEMISTRY

YOU MUST KNOW…• THE 3 SUBATOMIC PARTICLES

AND THEIR SIGNIFICANCE• THE TYPES OF BONDS, HOW

THEY FORM, AND THEIR RELATIVE STRENGTHS

CONCEPT 2.1• MATTER CONSISTS OF

CHEMICAL ELEMENTS IN PURE FORM AND IN COMBINATIONS CALLED COMPOUNDS

MATTER• TAKES UP SPACE AND HAS

MASS• ELEMENT – CANNOT BE

BROKEN DOWN TO OTHER SUBSTANCE BY A CHEMICAL REACTION

• COMPOUND – MADE OF 2 OR MORE ELEMENTS COMBINED IN A FIXED RATIO

ELEMENTS• C, H, O, N MAKE UP 96% OF

LIVING MATTER• ABOUT 25 OF THE 92

NATURAL ELEMENTS ARE KNOWN TO BE ESSENTIAL TO LIFE

• TRACE ELEMENTS ARE REQUIRED IN ONLY MINUTE QUANTITIES

CONCEPT 2.2• AN ELEMENT’S PROPERTIES

DEPEND ON THE STRUCTURE OF ITS ATOMS

ATOM• ATOMS ARE THE SMALLEST

UNIT OF AN ELEMENTS THAT STILL RETAINS THE PROPERTY OF THE ELEMENT

PROTONS• PROTONS – POSITIVELY

CHARGED PARTICLES• FOUND IN THE NUCLEUS AND

DETERMINE THE ELEMENT

ELECTRONS• ELECTRONS – NEGATIVELY

CHARGED PARTICLES• FOUND IN ELECTRON SHELLS• DETERMINE THE CHEMICAL

PROPERTIES AND REACTIVITY OF THE ELEMENT

NEUTRONS• PARTICLES WITH NO CHARGE• FOUND IN THE NUCLEUS• THEIR NUMBER CAN VARY IN

THE SAME ELEMENT CREATING ISOTOPES

ATOMIC NUMBER/MASS

• ATOMIC NUMBER IS THE NUMBER OF PROTONS AN ELEMENT POSSESSES

• UNIQUE TO EVERY ELEMENT• MASS NUMBER OF AN

ELEMENT IS THE SUM OF ITS PROTONS AND NEUTRONS

CONCEPT 2.3• THE FORMATION AND

FUNCTION OF MOLECULES DEPEND ON CHEMICAL BONDING BETWEEN ATOMS

CHEMICAL BONDS• DEFINED AS INTERACTIONS

BETWEEN THE VALENCE ELECTRONS OF DIFFERENT ATOMS

• ATOMS ARE HELD TOGETHER BY CHEMICAL BONDS TO FORM MOLECULES

COVALENT BOND• OCCURS WHEN VALENCE

ELECTRONS ARE SHARED BY 2 ATOMS

NONPOLAR COVALENT BONDS

• OCCUR WHEN THE ELECTRONS BEING SHARED ARE SHARED EQUALLY BETWEEN THE TWO ATOMS

• EX. O = O, H – H• ATOMS VARY IN THEIR

ELECTRONEGATIVITY (THE TENDENCY TO ATTRACT ELECTRONS OF A COVALENT BOND)

POLAR COVALENT BONDS

• ONE ATOM HAS GREATER ELECTRONEGATIVITY THAN THE OTHER, RESULTING IN AN UNEQUAL SHARING OF THE ELECTRONS

• EX. WATER

IONIC BOND

• TWO ATOMS ATTRACT VALENCE ELECTRONS SO UNEQUALLY THAT THE MORE ELECTRONEGATIVE ATOMS STEALS THE ELECTRON AWAY FROM THE LESS ELECTRONEGATIVE ATOM

HYDROGEN BOND

• RELATIVELY WEAK BONDS THAT FORM BETWEEN THE POSITIVELY CHARGED HYDROGEN ATOM OF ONE MOLECULE AND THE STRONGLY ELECTRONEGATIVE OXYGEN OR NITROGEN OF ANOTHER MOLECULE

VAN DER WAALS INTERACTIONS

• VERY WEAK, TRANSIENT CONNECTIONS THAT ARE THE RESULT OF ASYMMETRICAL DISTRIBUTION OF ELECTRONS WITHIN A MOLECULE

• CONTRIBUTES TO THE 3-D SHAPE OF LARGE MOLECULES