Presentation on theme: "Ch 2 The Chemistry of Life"— Presentation transcript:
1 Ch 2 The Chemistry of Life 2.1 The Nature of Matter
2 Atoms Basic unit of matter May be broken into smaller particles that do NOT have the properties of the element.
3 AtomsVery small- 100 million atoms would make a row only about 1 centimeter longConsists of protons, neutrons, and electrons.
4 Atoms Nucleus Protons Neutrons Electrons Core of atom Positive charge, in nucleus, mass of 1 atomic unitNeutronsNo charge, in nucleus, mass of 1 atomic unitElectronsNegative charge, orbits nucleus, mass of 0 atomic units (technically a mass of 1/1840).
5 Carbon AtomAtoms have equal numbers of electrons and protons, their positive and negative charges balance out, and atoms themselves are electrically neutral.
6 Matter is made up of atoms Atoms join together to make compounds Compounds use chemical bonds to hold them togetherChemical bonds are stored energyMoleculeAtoms of the same element joined together.
7 Elements and IsotopesElements and isotopes have same number of electronsAll isotopes of an element have the same chemical properties.
8 Elements Pure substance that consists entirely of one type of atom or Elements cannot be broken down into other types of substancesMercury (Hg).
9 IsotopesAtoms of the same element that differ in the number of neutrons.
10 Atomic Number (atomic mass or weight) Number of protonsAtomic Number (atomic mass or weight)Number of protons and neutrons.
12 Radioactive IsotopesNuclei are unstable and break down at a constant rate over timeUsed forDetermine the ages of rocks and fossils by analyzing the isotopes found in themDetect and treat cancerKill bacteria that cause food to spoilLabels or “tracers” to follow the movements of substances within organisms.
13 Chemical CompoundsSubstance formed by the chemical combination of two or more elements in definite proportionsWater, the chemical formula H2O, contains two atoms of hydrogen for each atom of oxygen.
14 Chemical CompoundsPhysical and chemical properties of a compound can be different from the elements that forms itSodiumReacts explosively with cold waterChlorineVery reactive, poisonous, greenish gas that was used in battles during World War ISodium ChlorideTable salt.
15 Chemical BondsAttraction between two atoms resulting in a sharing or transferring of an electron(s)Uses electronsCovalent BondChemical bond that SHARES electronsIonic BondChemical bond that TRANSFERS electronsHydrogen BondWeak bond between hydrogen ions.
17 Ionic Bond Transfer of electron(s) Ion A charged particle Protons do NOT equal electrons
18 Ionic BondA sodium atom easily loses its one valence electron and becomes a sodium ion (Na+).
19 Ionic BondA chlorine atom easily gains an electron (from sodium) and becomes a chloride ion (Cl-).
20 Van der Waals ForcesSlight attraction can develop between the oppositely charged regions of nearby moleculesDue to unequal sharing of electrons within each moleculeMuch weaker than Covalent of Ionic bonds.