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Chemistry of Life Sect 6.1

Chemistry of Life Sect 6.1. Atoms and Their Interactions. CONSERVATION OF MATTER : MATTER CAN NOT BE CREATED OR DESTROYED 1. Physical change – does not alter identity of the substance Crushing and tearing 2. Chemical change – alters identity Burning, corrosion, and rusting. carbon.

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Chemistry of Life Sect 6.1

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  1. Chemistry of LifeSect 6.1 Atoms and Their Interactions

  2. CONSERVATION OF MATTER: MATTER CAN NOT BE CREATED OR DESTROYED 1. Physical change – does not alter identity of the substance • Crushing and tearing 2. Chemical change – alters identity • Burning, corrosion, and rusting

  3. carbon calcium Elements 1. Element –substance that can not be broken down --92naturally occurring elements --96% of Living things are composed mostly of carbon, nitrogen, oxygen and hydrogen red phosphorous nodules copper gold nickel sulfur

  4. Trace Elements --Elements required by living organisms in very small amounts --all are metals Ex. Iron, Copper, Zinc, Iodine, Chromium

  5. Atom- smallest particle of an element with traits of the element Nucleus – located at the center of atoms Proton – positively charged particle Neutron – neutrally charged particle Electrons – negatively (-) charged particles orbit the nucleus in the electron cloud NEUTRON PROTON ELECTRON

  6. Elements have distinct traits due to the number of protons in the nuclei of the atoms. Electrons orbit the nucleus at the speed of light forming an electron cloud. Electrons of different energy levels will form clouds closer or further from the nucleus.

  7. Electron Energy Levels 1st energy level – holds maximum two electrons 2nd energy level – holds maximum eight electrons 3rd energy level – holds maximum eighteen electrons At. # = 10 Neon

  8. Isotopes of Elements Isotopes – atoms of same element having different # of neutrons See Problem-Solving Lab pg. 145 -Some isotopes are radioactive (give off energy or particles that can kill cells) -used in medicine to treat cancers.

  9. Using the Periodic Table Carbon 6 C 12.01 1. Name of the element 2. Atomic Number -Number of protons 3. Symbol for the element 4. Atomic Mass = Average mass of the nucleus

  10. Information about Atoms Protons = Electrons (if atom is electrically neutral) Atomic Number =# of protons (+) and = # of electrons (-) Mass # =# of Protons + # of Neutrons Carbon 12

  11. Compound – a substance composed of atoms • of different elements • Example: H2O = Two hydrogen atoms bonded • with one oxygen atom One Water (H2O) Chemical Formula = H2O

  12. Chemical Bonds* --hold atoms together --Most atoms bond by ‘sharing’ electrons. --Atoms bond and become ‘stable’ when they fill their outermost energy level. *only involve valenceelectrons

  13. All atoms want to fill their outer energy level!! Valence # = # of electrons in the outermost energy level of an atom

  14. Covalent bonds– bonds that form when two or more atoms share electrons Molecule – a group of atoms held together by covalent bonds

  15. Covalent bonds • - electrons are shared equally • -very strong • -very stable (do not break easily) write

  16. Ionic bonds – formed by attractive force between two or more ions of opposite charge Na + Cl Na+Cl- Sodium loses an electron to Chlorine. The charged ions are now held together. -Strong bonds except in water!! IONIC BOND ANIMATION

  17. Ion – an atom that has lost or gained electron(s) Na+ (lost an electron) NaCl + Cl-(gains an electron) water

  18. Chemical Reactions – when bonds are formed or broken, causing substances to recombine into different substances Metabolism – all the chemical reactions that occur within an organism 1. Breakdown compounds 2. Build new compounds -Substances that undergo chemical reactions = Reactants -Substances formed by chemical reactions = Products 1. Coefficient # indicates the # of molecules of a substance 2. Subscript # indicates the # of atoms of each element present

  19. Mixtures and Solutions • Mixture - combination of substances in which individual substances retain their own properties (can separate) • Example: Rocks in water

  20. Solution - a mixture in which one or more • substances are distributed evenly in • another substance (do not separate). • --substance that dissolves = solute • --substance causeing dissolving = solvent • Ex.: Sugar in water • Latex paint in water Solutions

  21. Acids and Bases Acid – any substance that forms hydrogen (H+) ions in water Ex. HCl (Hydrochloric Acid), H2SO4,(Sulfuric Acid) Base – any substance that forms hydroxide ions (OH-) in water Ex. NaOH (Sodium Hydroxide)

  22. pH scale – numeric scale that measures • how acidic or basic a solution is • Values range from: • 0(most acidic) to 14( most basic) • 7 is neutral (H+ = OH-)

  23. Stomach acid = 2 Blood = 7.3 Urine = 6.5 – 6.9

  24. Acidic solution • -----more H+ • -----pH less than 7 • 2.Basic solution (alkaline solution) • -----more OH- • -----pH greater than 7

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