Physical Science: Ch 6 Notes A. Atoms Bond to form Compounds Compound- a substance that is composed...
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Transcript of Physical Science: Ch 6 Notes A. Atoms Bond to form Compounds Compound- a substance that is composed...
Physical Science: Ch 6 NotesA. Atoms Bond to form Compounds
Compound- a substance that is composed of two or more different elements joined in a fixed proportion
Chemical bond- the force that holds atoms together
Covalent bond- a chemical bond in which two atoms (both nonmetals!) share a pair of valence electrons
Ionic bond- a chemical bond that forms between atoms of a metal and a nonmetal
Form when electrons are transferred from one atom to another
Results in the formation of ions – atoms that have a net positive or negative electric charge
This charge is due to the loss or gain of electrons
This transferring of electrons allows electricity to flow through solutions of ionic compounds
Physical Science: Ch 6 NotesCation – an ion with a positive charge (due to loss of electrons)
Anion – an ion with a negative charge (due to gain of electrons)
Naming ionic compoundsexamples: magnesium chloride
copper sulfidezinc oxide
the trend: cation anion-ide
Molecule – a neutral group of atoms (nonmetals!) that are joined together by one or more covalent bonds
The attractions between the shared electrons and the protons in each nucleus hold the atoms together in a covalent bond
Molecules are named using prefixes that describe the number of atoms of each element in the molecule
Physical Science: Ch 6 NotesPrefixes for naming COVALENTLY bonded molecules:1=mono 6=hexa2=di 7=hepta3=tri 8=octa4=tetra 9=nona5=penta 10=deca
Examples: N2O4 is dinitrogen tetraoxideP3F7 is triphosphorus heptafluorideNO2 is nitrogen dioxide
NOTICE: the second element still ends in –idethe prefix mono is not usually used for the first
element in the name (NO2 is nitrogen dioxide)
REMEMBER: When naming chemicals, prefixes are only used when nonmetals are bonded (COVALENT MOLECULES)! Prefixes are NOT used for naming Ionic Compounds.
Physical Science: Ch 6 NotesB. Properties of Ionic and Covalent chemicals
IONIC COVALENT
-usually solid at room temperature
-have high melting and boiling points
-forms solid crystals
-solutions of ionic compounds conduct electricity
-usually dissolve in water very well
-usually liquid or gas at room temp
-lower melting and boiling points
-does not form solid crystals
-solutions do not conduct electricity
-usually do not dissolve in water very well
Physical Science: Ch 6 NotesC. Metals
Alloy – a mixture of two or more elements, at least one of which is a metal
Bronze – alloy of copper and tin metals
Brass – alloy of copper and zinc metals
Steel – alloy of iron with small quantities of carbon