Elements and the Periodic Table (Chapter 4, sections 1 and 2)
CUE WORDS or QUESTIONS
What is an atom?
NOTES WRITTEN
Atom – the basic, individual particle of all elements
All atoms of the same element are exactly alike and have the same mass
An atom of one element cannot be changed into a different element
Every compound is composed of atoms of different elements in a specific
ratio (like H2O… two hydrogen for every one oxygen)
What charge do electrons
have?
Electrons – negatively charged particles in an atom
Atoms are mostly empty space because electrons are so far from the nucleus
Electrons have different energy levels (rings) depending on its distance to
the nucleus
Electron cloud- region surrounding the nucleus that electrons can be found
Electrons surround a nucleus (nuclei-plural), made of protons and neutrons
What charge do protons have?
What charge do neutrons have?
Protons- positively charged particles in an atom
Neutrons- neutral particles in an atom (they have no charge)
For an uncharged atom, the proton number equals the electron number
Particles in an Atom
Subatomic
Particle
Symbol
Charge
Relative
Mass (amu)
Location
Proton
P+
+1
1
Nucleus
Neutron
n
0
1
Nucleus
Electron
e-
-1
1__
1,836
Electron
cloud
Atoms are almost inconceivably tiny, there are 9 sextillion atoms in a penny
(9,000,000,000,000,000,000,000)
Atomic number-
SUMMARY
Atomic number- every atom has a set number of protons, if it has a different
number of protons then it is a different element!!
Carbon has 6 protons, nitrogen has 7 protons, & oxygen has 8 protons…
(What is the atomic number for carbon? For nitrogen? For oxygen?)
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NOTES WRITTEN
The atomic number is fixed and unchanging, but the number of neutrons
can change (as this does not change the overall charge of the atom)
What happens if the
Isotope- atom of an element that has a different number of neutrons
number of neutrons changes? Isotopes are identified by their mass number (ex- Carbon 14)
Mass number- sum of protons and neutrons
(Why are only protons and neutrons counted in the mass of the atom?)
What is the periodic table?
Periodic table- how elements are organized on a chart based on the
properties of the atoms
There are over 100 different elements, the properties of an element can be
predicted based on its location on the periodic table
How are elements
Each element on the periodic table has an atomic number, chemical symbol,
represented?
Chemical symbol-
element name, and atomic mass
Chemical symbol- representation of an element consisting of one or two
letters, some based on English name while others based on Latin
N represents nitrogen while Fe represents iron
Atomic mass- average mass of all of the isotopes for an element
The neutron number can be calculated by subtracting the atomic number
from the atomic mass
Atomic mass-
Different classes of elements- metals, semimetals, nonmetals, & inert gases
Reading a periodic table-
SUMMARY
Periods- horizontal rows
Contains very different elements & increases in proton number by one
Groups (families)- vertical columns
Contains very similar elements & increases orbital number by one
Group 1 reacts violently with water, group 17 reacts violently with Group 1