1. “Chemical Interactions”

2. is
the study of
matter
and
its changes.

3. “Atoms are the Smallest Form of Elements”
Unit D Chapter 1.1
pages D9 – D16
“Atoms are the Smallest Form of Elements” f

4. consists of atoms of only one type
element               
a substance that cannot be broken down into a simpler substance by ordinary chemical changes
consists of atoms of only one type

6. The most common element in the universe
is...
HYDROGEN

7. Hydrogen atoms make up only about 1% of Earth’s crust.
Atoms of the element hydrogen account for about 90% of the total mass of the universe.
Hydrogen atoms make up only about 1% of Earth’s crust.
Most of those hydrogen atoms are combined with oxygen atoms in the form of...
water ?

8. ATOMIC CHEMICAL SYMBOLS
one or two letters chosen to represent an element
H = hydrogen Ne = neon
The origin of some chemical symbols comes from Latin names.
Au= gold
aurum

9. What is the size of one atom? It is estimated that about
one trillion (1,000,000,000,000) atoms
would fit into a period
at the end of
this sentence.

10. The three subatomic particles that make up atoms are...
THE STRUCTURE OF
The three subatomic particles that make up atoms are...
protons,
neutrons,
and electrons.

11. a positively charged particle located in an atom's nucleus
proton
a positively charged particle located in an atom's nucleus

12. neutron               
a particle that has no electric charge and is located  in an atom's nucleus

13. nucleus                
the central region of an atom where most of the atom's mass is found in protons and neutrons

14. The nucleus is held together by the "strong nuclear force."
This force between
the protons and neutrons
overcomes the electrical force of repelling that would push
the positively charged protons apart.

15. electron             
a negatively charged particle located outside an atom's nucleus
about 2000 times smaller than either a proton or neutron

16. SUBATOMIC PARTICLES Protons and neutrons are heavier than electrons
and exist in the "nucleus,"
which is the center of the atom.
Protons have a
positive electrical charge,
and neutrons have
no electrical charge. 
Electrons are extremely lightweight
and are negatively charged.
They exist in a cloud that surrounds the atom.

17. ELECTRON SHELLS
Electrons spin very quickly around the nucleus of an atom.
Electrons spin around the atom in pathways called orbitals or shells. 

18. a carbon atom's two electron shells
The innermost shell (or lowest energy level) is filled first, and each succeeding shell can only hold a certain number of electrons before it becomes full.
a carbon atom's two electron shells

19. atomic number 
number of protons in the nucleus of an atom (also same as number of electrons in a neutral atom)

20. atomic mass number the total number of protons and neutrons
in an atom's nucleus

21. atomic mass number                

22. isotope   
an atom of one element that has a different number of neutrons than another atom of the same element

23. isotope   
ATOMIC NUMBER
ATOMIC MASS NUMBER

24. isotope   

25. the RED particles are protons.
isotope   
EXAMPLES
                                                                                                                        In this figure, the YELLOW particles are orbital electrons, the BLUE particles are neutrons and
the RED particles are protons.

26. Atomic Mass How heavy is an atom of oxygen?
It depends.. b/c there are different oxygen isotopes.
We are more concerned with the average atomic mass.
This is determined based on the abundance of each isotope
We don’t use grams for this mass because the numbers would be too small.

27. Measuring Atomic Mass Instead we use the Atomic Mass Unit (amu)
defined as one-twelfth the mass of a carbon-12 atom.
Each isotope has its own atomic mass, thus we determine the average from percent abundance.

28. Composition of the nucleus
Atomic Mass
Atomic mass is the average of all the naturally occurring isotopes of that element.
Isotope
Symbol
Composition of the nucleus
% in nature
Carbon-12
12C
6 protons
6 neutrons
98.89%
Carbon-13
13C
7 neutrons
1.11%
Carbon-14
14C
8 neutrons
<0.01%
Carbon =

29. NEUTRAL ATOM EQUAL In a neutral atom (without an electric charge),
the number of protons (positive charge)
and the number of electrons (negative charge)
are…
EQUAL

30. an atom or group of atoms that has a positive or negative
ion              
an atom or group of atoms
that has a positive or negative
electric charge
forms by atoms
gaining or losing
electrons

31. electrons (negative charges).
ion              
A POSITIVE ION is formed when an atom loses
electrons (negative charges).
Na+ = sodium loses 1 electron
Ca2+ = calcium loses 2 electrons

32. electrons (negative charges).
ion              
A NEGATIVE ION is formed when an atom gains
electrons (negative charges).
Cl- = chlorine gains 1 electron
O2- = oxygen gains 2 electrons

33. ion When an ion (a charged atom) is formed, the number of protons
does not change.