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Compounds and Molecules

Compounds and Molecules. The silvery metal sodium + poisonous, yellowish green chlorine gas = (in a violent reaction) to form white granules of table salt (NaCl) that you can eat Table salt is a compound made of two elements, ____________ and __________

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Compounds and Molecules

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  1. Compounds and Molecules

  2. The silvery metal sodium + poisonous, yellowish green chlorine gas = (in a violent reaction) to form white granules of table salt (NaCl) that you can eat • Table salt is a compound made of two elements, ____________ and __________ • Compound has properties very different from those of the elements that make it

  3. Chemical bond- the attractive force that hold atoms or ions together • Compounds are always made of the same _________ in the same proportion • Ex: Water molecule, is always made of 2__ ___ and one ____ ____ • Chemical structure – the arrangement of atoms in a substance • You can see how a compound’s atoms or ions are connected by its chemical structure

  4. Two terms are used to specify the positions of atoms relative to one another in a compound: bond length and bond angle • Bond length- the average ________ between nuclei of two bonded atoms • Bond angle- the angle formed by two ____to the same atom • Ex: water bond length= ______ (pico =1x10-12) bond angle= _______

  5. Quartz, has the chemical formula SiO2 • The bonds that holds these atoms are very strong • This why rocks containing quartz are hard and inflexible solids • Compounds with network structures are strong solids

  6. Table salt, NaCl sodium chloride, is found in regularly shaped crystals • Like quartz, is made of repeating network connected by strong bonds • The network is made of = charged ______ ions, and negatively charged ____ ions Some compounds are made of network of bounded ions

  7. A molecule of sugar, C12H22O11 is made of atoms joined by bonds • Molecules of sugar attract each other to form crystals but these attractions are much weaker than those that hold bonded _______, _______ and_______ atoms together to make sugar molecule • Some compounds are made of molecules

  8. Three different kind of bonds describe the way atoms bond in most substances: -ionic bond -metallic bond -covalent bond Atoms bond when their valence electrons interact Atoms with full outermost s and p orbitals are more stable than atoms with only partly filled outer sand p orbitals

  9. Ionic bonds are formed between oppositely charged ions • Give examples of positive and negative charged ions:_____________________ • Some atoms do not share electrons to fill their outermost energy level completely, they transfer _____ (ex: Na+ Cl-) • Ionic bonds are formed by the transfer of electrons

  10. Ionic compounds are in the form of networks, not molecules

  11. Metallic bonds

  12. Metals like copper, can conduct electricity, when they are solid • Metals are so flexible, so they can bend and stretch without breaking, because the atoms can slide past each other without breaking • The attraction between one atom’s nucleus and a neighboring atom’s electrons pack the atoms closely together • Metallic bond- formed by attraction between positively charged metal ions and the _________around them

  13. Covalent bond

  14. Before bonding each atom has _ electrons in its outermost energy level • The atoms don’t transfer electrons to one another because each needs to gain an electron • If each atom shares one electron with another atom, then both atoms together have a full outermost energy level (8 electrons

  15. Compounds that are made of molecules, like water and sugar, have covalent bonds • Covalent bonds are often formed between nonmetal atoms • Covalent bond- a bond formed when atoms share one or more pairs of _____ • Atoms may share more than one pair of electrons

  16. The elements oxygen and nitrogen have covalent bonds • Electrons not involved in bonding are represented by dots • The bond joining 2 O atoms is represented by 2 lines (total of four electrons) form a double covalent bond • The bond joining 2 N form a triple covalent bond (total of__ e-)

  17. The bond between two nitrogen atoms is stronger than the bond between two oxygen atoms, more energy is required to break the bond • Atoms do not always share electrons equally (ex: NH3) • An unequal sharing of electrons forms a polar covalent bond.

  18. Compounds that have either ionic or covalent bonds. • Some compounds have both ionic and covalent bonds. • Such compounds are made of polyatomic ions • Polyatomic ionsare groups of covalently bonded atoms that have either _____ or ______electrons. • A polyatomic ion acts the same as the ions you have already encountered.

  19. Ex: -baking soda, sodium hydrogen carbonate, NaHCO3. -Hydrogen carbonate, HCO3-, is a polyatomic ion. - Sodium carbonate Na2CO3, is often used to make soaps and other cleaners and contains the carbonate ion, CO32-

  20. -Sodium hydroxide, NaOH, has hydroxide ions, OH-, and is also used to make soaps. -Ammonium nitrate, NH4NO3, and ammonium sulfate, (NH4)2SO4, both contain positively charged ammonium ions, NH4+ . -Nitrate, NO3- , and sulfate SO42-, are both negatively charged polyatomic ions

  21. Why the chemical formula for ammonium sulfate is written as (NH4)2SO4 instead of as N2H8SO4. -The parentheses around the ammonium ion are there to remind you that it acts like a single _____. -There are two ammonium ions for every sulfate ion. -A polyatomic ion’s charge applies not only to the last atom in the formula but to the entire ion

  22. -Many polyatomic anions are made of oxygen. -Most of their names end with -ite or -ate. sulfate (SO42-) and sulfite(SO32-), nitrate (NO3-) and nitrite (NO2-), chlorate (ClO3-) and chlorite (ClO2-). The ions have different numbers of ____ atoms. (their names also have different endings) An -ate ending is used to name the ion with one more oxygen atom. The name of the ion with one less oxygen ends in -ite.

  23. 1. Classify the following substances as mixtures or compounds: a. air c. SnF2 b. CO d. pure water 2. Determine if the following compounds are likely to have ionic or covalent bonds. • magnesium oxide, MgO • strontium chloride, SrCl2 c. ozone, O3 d. methanol, CH3OH

  24. 3. Draw the structural formula for acetylene. Atoms bond in the order HCCH. Carbon and hydrogen atoms share two electrons, and each carbon atom must have a total of four bonds. How many electrons do the carbon atoms share?

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