Science Unit 3: Chemistry, atoms, molecules; October 20, 2014
H3 PO3
7 atoms in each molecule
How many atoms are there in just one molecule of blood?
9,512
metallic bond
A bond formed by the attraction between positively charged metal ions and the electrons around them
cations have positive charges. Anions have negative charges. What force draws the two together?
electrostatic attraction
the atoms of a molecule come from two or more
elements
formula
short way of writing a compound
symbol
short way of writing an element
a chlorine atom has seven electrons and needs one additional electron to become
stable
Formula: HgO Named: mercuric oxide: Elements: Mercury (Hg) Oxygen (O) what is the number of atoms of each element and total number of atoms in one molecule
(hg) one atom; (O) one atom; total number of atoms: 2
HF
2 atoms in each molecule
what makes a molecule of oxygen gas?
2 oxygen atoms bonded together makes a molecule of oxygen gas
the total number of atoms in one molecule of starch is 6, 10, 16, 21
21
what is a formula?
A formula tells us which elements there are in a molecule. it also tells us how many atoms there are of each element. The formula for a compound is always the same. A change in the formula means that a new substance was formed.
Atom X has 10 electrons. Atom Y has eight electrons. which of them is more likely to bond with another atom?
Atom Y
what is the formula for starch?
C6 H10 O5. this stands for one molecule of starch.
balanced equation
Chemical equation with the same number of atoms of each element on both sides of the equation
law of conservation
Matter is not created nor destroyed in any chemical or physical change
what is the difference between atoms and molecules?
Molecules are made up of atoms. Each element on the periodic table of elements is made up of one single type of atom. molecules are formed when atoms bond. Different types of atoms can form together to make a molecule.
substance M is a blue, brittle solid. Substance N is a colorless, flammable gas. What can we predict about the compound created when M and N for a covalent bond?
There's no way to tell based on the information given
next, the coefficients are chosen to make the number of
______________ balance.
physical change
a change that effects one or more physical properties of a substance, many physical changes are easy to undo.
chemical change
a change that occurs when one or more substances are changed into entirely new substances with different properties, can not be reversed in any physical means
atoms that combine by sharing electrons form what
a covalent bond. An example is chlorine 2 sharing electrons; H2O are sharing
when two or more atoms bond this way they form a neutral particle called
a molecule
molecule
a neutral group of atoms held together by covalent bonds
coefficient
a number place in front of a chemical symbol or formula, used to balance a chemical equation
compound
a pure substance composed of two or more elements that are chemically combined
chemical equation
a shorthand description of a chemical reaction using chemical formulas and symbols
chemical formula
a shorthand notation for a compound or a diatomic element using chemical symbols and numbers
what is a symbol?
a written sign used instead of a word to represent something
which of the following atoms is most likely to bond with another atom?
an atom with 9 electrons
how many atoms of each of the following elements are in one molecule:
carbon: 3032; hydrogen: 4816; oxygen: 872; nitrogen: 780; sulfur: 8; iron: 4
a molecule is made up of?
atoms
opposite charges do what
attract each other
Coefficients are necessary to keep the numbers of atoms in
balance
You can only use coefficients to
balance the number of atoms on each side of the equation.
don not change the correctly written formula. If you change the formula of substance, the reaction is no longer
balanced
to show atoms are not lost or created during a reaction, the equation is
balanced
the number of molecules in a teaspoon of starch is twenty-one or billions
billions
C3032 H4816 O872 N780 S8 Fe4 a very special large molecule has thousands of atoms what is it called?
blood
a balanced chemical equation shows the same number of each kind of atom on
both sides of the arrow
write the number of atoms in CO2
carbon 1, oxygen 2
write the number of atoms in C55 H12 MgN4 O5
carbon 55, hydrogen12, magnisium 1, nitrogen4, oxygen 5
write the number of atoms in C6 H12 O6
carbon 6, hydrogen 12, oxygen 6
a group of symbols that represent a compound is a
chemical formula
the numbers that are placed on front of the symbols and formulas are called
coefficients
chlorine gas exists as particles made up of
compound of chlorine atoms.
CaF2
contains one kind of atom
element
contains one kind of atom
Atoms that combine by sharing electrons form a
covalent bond
This sharing of a pair of electrons is called a
covalent bond
symbols can be used for the states of mater:
cr or s = crystal or solid. l = liquid, g = gas, and aq = aqueous
what do hydrogen atoms and one oxygen atoms do? and HOw?
create water by bonding together
equations are balanced to show that atoms are not lost or
created during a reaction just rearranged.
A solid that has particles in a regular repeating pattern is called a
crystal
Elements such as chlorine form chlorine form molecules with two atoms are called
diatomic molecules
a compound is a substance formed when
elements combine chemically. This kind of change results in a compound with properties that my be very different from the elements that form it.
A way to show the changes that take place in a chemical reaction is to write a chemical
equation
the short hand method is
faster than writing than writing the word description of the reaction
there are more or fewer elements than compounds?
fewer
an atom has 15 total electrons. How many electrons does it have in its outer shell?
five
to balance an equation, first write the correct
formula for each reactant and ----------
atoms share, gain, or lose electrons in order to
have 8 electrons in their last energy level
when atoms combine chemically a bond is formed that
holds the atom together
write the number of atoms in H2O
hydrogen 2, oxygen 1
a charged particle is called an
ion
when a neutral atom loses or gains one or more electron, charged particle that results is called an
ion
Atom A has 7 electrons in its outer shell. Atom B has 1 electron in its outer shell. After bonding, both atoms now have 8 electrons in their outer shells. What kind of bond is
ionic
When ions bond together it is called
ionic bonding
bonding that occurs between ions is called
ionic bonding
Elements and what can form molecules?
ions
besides the formulas for the substances involved in the reaction, an arrow present to show what
is prduced
the relationship between the number of electrons in an atom's outer shell and the atom's tendency to bond is called the octet rule. What can you infer about the meaning of the
it refers to sets of eight
based on what you know about atomic structure, what can you infer about the word "nuclear?"
it relates to protons and neutrons
if an atom has no charge, which of the following must be true?
its number of protons is equal to its number of electrons
molecules are larger or smaller than atoms?
larger
by sharing, each chlorine atom has eight electrons in its outer energy what?
level
reactions between chemicals sometimes depend on the substances state of
matter. For example, some solid chemicals will not react when mixed together, but they will react when they are mixed in state
The ionic compound is different from this new particle, which is called a
molecule
When two or more atoms bond covalently, they form a neutral particle called a
molecule
when atoms bond covalently, there are no charges and the new particle is
neutral
can a single atom be considered a molecule?
no, it takes two or more atoms bonded to create a molecule
the neighboring chlorine atom is similar, thus they each share
one electron
write the number of atoms in O2
oxygen 2
molecules can be made up of two atoms of the same element; for example:
oxygen gas is made up only of oxygen atoms
In the ionic compound, instead of new molecules formed there is an orderly arrangement of
pairs
the atom that loses one or more electrons results in a
positive charge, while the atom that gains one or more electron results on a negative charge.
Formula: KCl; Name: potassium chloride; elements: potassium (K); chlorine (Cl) what is the number of atoms of each element and total number of atoms in one molecule
potasssium (K) has one atom; chlorine (Cl) has one atom; total number of atoms in one molecule is 2
Some substances are not soluble in water and when they are formed they will
precipitate out of a solution
substances to the right (or after) the arrow are the
product
any substances that are listed to the right of the arrow are called
products
elements in a compound always combine in the same
ratio. Ex. the ratio of carbon to oxygen in carbon monoxide (CO) is 1 to 1, and in carbon dioxide is 1 to 2
substances to the left (or before) the arrow are the
reactants
The smallest number in a formula that shows how many atoms of an element are present in a
subscript
when this is done, there will be the same number of each kind of
substance on both sides of the arrow
changing a formula will indicate a different
substance than the one indicated.
therefore it is necessary to note what state the substances are in by the use of
symbols
a chemical equation shows changes that take place during a chemical reaction using
symbols and formulas
One molecule of starch has two, six, ten atoms of hydrogen
ten
valence electron
the electrons in the outermost energy level of an atom. these electrons are involved in forming chemical bonds
ionic bond
the force of attraction between oppositely charged ions
covalent bond
the force of attraction between the nuclei of atoms and the electrons shared by the atoms
reactants
the starting materials in a chemical reaction
products
the substances form from a chemical reaction
numbers called coefficients are used in front of symbols and formulas (such as 2HCl) so
these numbers keep the number of atoms in balance.
starch is made up of one, two, three elements?
three
the number of different kinds of atoms in starch is
three
why does the author describe the atoms that make up water?
to give an example of a specific molecule
a single molecule has at least one or two atoms?
two
water molecules are made up of?
two hydrogen atoms and one oxygen atom
compound
two or more different kinds of atoms linked together
Explain why understanding bonding is important for understanding molecules.
understanding bonding is more important for understanding molecules because if atoms don't bond they can't make a molecule. (molecules can't exist without atoms)
when reading this reaction the arrow is read as
yields
the arrow in a chemical equation means
yields or produces
