Science chapter 11- lesson 2, Compounds, chemical formulas and covalent bonds
When you look at the chemical formula CO2 it tells you:
2 atoms of oxygen combined with one atom of carbon
ball and stick formula
3 balls representing the elements with stick lines connecting them
Chemical Bonds
Chemical bonds join atoms together. It is a force that holds atoms together in a compound.
structural formula
O=C=O
space filling model
OOO
Covalent Bond
When unstable, nonmetal atoms bond together, they bond by sharing valence electrons. A covalent bond is a chemical bond formed when two atoms share one or more pairs of valence electrons. The atoms then form a stable covalent chemical compound.
covalent bond
a chemical bond formed when tow or more atoms share one or more pairs of valence electrons
molecule
a group of atoms held together by covalent bonding that acts as an independent unit
chemical formula
a group of chemical symbols and numbers that represent the elements and the numbers of atoms of each element on a compound
Polar molecule
a molecule that has a slight positive end and a slight negative end because of UNEQUAL sharing of electrons
compound
a substance made up of two or more different elements. Compounds and the elements that make them often have different properties.
Polar molecules, such as sugar and water, _________ easily in one another because the attraction of opposite charges
dissolve
polar compounds ______ in polar
dissolve
_____________ covalent bonds are not as strong as triple but stronger than single
double
The letters in a chemical formula represent the
element
the letters in a chemical formula represent the ______________
elements
In a carbon dioxide molecule, a double covalent bond forms when the carbon atom shares _______pairs of valence electrons with each oxygen atom
equal- picture:
In a non polar molecules share electrons _______________
equally
like dissolves _________
like
covalent conductors have __________ melting and boiling points
low
characteristics of covalent compounds are:
low melting point, low boiling point and poor conductors of electricity and thermal energy
element
made up of one type of atom, but compounds are chemical combinations of different types of atoms.
Molecules made up of atoms of the SAME element are ________________ because the atoms are identical
non polar
non-polar can dissolve in _________________
non polar
an example of a non-polar
oil
In a ____________________ covalent bond, three pairs of valence electrons are shared between 2 atoms
one triple- picture
In a molecule of water, the ________ atom attracts the electrons more strongly than each hydrogen atom
oxgen
Because the electrons have a slightly negative charge, there is a slight negative charge near the ______ atom, there is a slight ______ charge near the hydrogen atom.
oxygen, positive
In a hydrogen molecule a ______ covalent bond forms when each atom shares its valence electrons with the other
polar- picture:
covalent conductors are _________ conductors of electricity and thermal energy.
poor
compounds and the elements that form them often have very different chemical and physical __________________
properties
non polar O=C=O shows
pulled equally by carbon and oxygen atoms
when forming water- valence electrons are _________ between oxygen and hydrogen atoms (which are unstable other own) therefore forming covalent bonds to make 3 stable atoms
shared
Dot diagram
shows elements that are being combined with their dots shown combining
____________ covalent bonds are the weakest of the 3 bonds
single
In a covalent bond, one atom can attract the shared electrons more _______ than the other atom can
strongly
the number in a chemical formula represent
the number of atoms of that element used in the compound
Polar O/h/h shows
the shared electrons are pulled closer to the oxygen atom than the hydrogen atom
_______ covalent bonds are strongest
triple
atoms can bond to form compounds by sharing ___________________________________________.
valence electrons
