Download nature of Matter

Class Notes
Topic: Nature of
Matter
Name: _______________________________________
Period:_______________________________________
Date: _______________________________________
Questions/Main
Idea:
What are atoms?
Notes:


Atoms are the smallest form of elements.
Atoms are the smallest particle of an element that has the chemical
properties of that element.
 Atoms are composed of protons, neutrons, and electrons.
Nucleus – Located in center of atom; contains both protons and neutrons.
Protons – Located in the nucleus; Positively charged
Describe the parts of an
atom.
What is an element?
What is atomic number?
What is mass number?
What is an isotope?
What is a compound?
What is a chemical
formula?
What is a chemical
bond?
Neutrons – Located in the nucleus; Neutral, No charge
Electrons – Move around outside of nucleus in a cloud; Negatively
charged. # of protons = # of electrons
It is a substance that consists of one type of atom.
There are over 100 known elements however, only two dozen are
found in living organisms.
Elements are represented by 1 or 2 letter symbols.
Ex: H for Hydrogen Cl for Chlorine.
The number of PROTONS in an element determines the element’s
atomic number.
Example:
 H has an atomic number of 1 so, it has only 1 proton in its
nucleus and consequently, 1 electron.
The mass number is the total number of protons and neutrons in
an atom’s nucleus.
Examples:
 Potassium-39 (19 protons & 20 neutrons)
 Uranium-235 (92 protons & 143 neutrons)
 Nitrogen-14 (7 protons & 7 neutrons)
An isotope is when atoms of the same element have a different
number of NEUTRONS.
Isotopes are identified by their mass number.
Since they still have the same number of electrons, all isotopes of
an element have the same chemical properties.
A compound is a substance made up of atoms of two or more different
elements.
It is a type of shorthand that uses chemical symbols to represent the
atoms and their ratios in a chemical compound.
Example:
 The compound water which contains two atoms of
hydrogen and one atom of oxygen, has the chemical
formula H2O.
 The ratio is 2:1
A chemical bond is the “glue” that holds two or more atoms together to
form a compound.
How are chemical bonds
formed?
How is an ionic bond
formed?
How is a covalent bond
formed?
What is a molecule?
Summary:
They form when the electrons of two or more atoms interact.
The electrons which are available for bonding are called valence
electrons.
Depending on how the electrons interact, the type of bond is
decided.
The main types of chemical bonds are Ionic & Covalent.
When electrons are transferred from one atom to another, an ionic
bond is formed.
An atom that loses electrons has a
+ charge.
An atom that gains an electron has a
– charge.
These + & - charged atoms are known as ions.
These oppositely charged ions have a strong attraction thus
forming the ionic bond.
When pairs of electrons are shared between atoms, this forms a
covalent bond.
The electrons actually travel in the orbitals of both atoms.
Single bond = 2 electrons
Double bond = 4 electrons
Triple bond =6 electrons
A molecule is a group of atoms held together by covalent bonds.
It can contain as few as 2 atoms or as many as a few thousand.
It is the smallest unit of most compounds.