Worksheet cloze activity

1. Grade 8 Science:Compounds, Chemical Formulas,and Chemical Bonds.
From Elementsto Compounds
1. A compoundisa substance thatis made up of two or more different
______________________
2. Compoundsandthe elementsthatformthemoftenhave verydifferent
chemical
and physical___________________________.
3. Atomscan bondto form compoundsby_________________valence
electrons.
CovalentBonds – Electrons Sharing
4. A covalentbondisa chemical bondformedwhentwoatoms
_______________ one or more pairs of valence electrons.
A Noble Gas ElectronArrangement.
5. An atomwithlessthaneightvalence electronsbecomesstable by
formingchemical bondsuntil ithas_________________valence
electrons.
Double and Triple CovalentBonds p. 342.
6. A single covalentbondexistswhentwoatomsshare _________ pairof
valence electrons.
7. A double covalentbondexistswhentwoatomsof share _________
pairsof valence electrons.
8. A triple covalentbond existswhentwoatomsshare three pairsof
valence electrons.
CovalentCompoundsp.342.
9. Whentwo or more atomsshare valence electrons,theyformastable
covalent____________________.
10. Covalentcompoundsusuallyhave ______ melting
and_______________ boilingpoint.
11. Theyare usually______________ and ______________ at room
temperature,butalsobe solids.
12. Covalentcompoundsare poorconductorsof thermal energyand
________________________.
Moleculesp.342.
13. A __________________ isa group of atoms heldtogetherbycovalent
bondingthatacts as an independentunit.
An example of acovalentcompoundis
___________________________________.
Water and Other Polar Moleculesp.343.
14. A molecule thathasa partial positive endandapartial negative end
because of unequal sharingof electronsisa______________
molecules.
Nonpolar Moleculesp.343.
15. A nonpolarcompoundwill noteasilydissolveina_______________
compound,butitwill dissolveinother nonpolarcompounds.
16. Polarcompoundcompoundscandissolve inother__________
compounds,nonpolarcompounds candissolve onother
________________ compounds.
Chemical Formulas and MolecularModelsp.344.
17. A ___________________ formulaisa group of chemical symbolsand
numbersthatrepresentthe elementsandthe numberof atomsof each
elementthatmake upthatcompound.