 # OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM

## Presentation on theme: "OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM"— Presentation transcript:

OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM
DETERMINE THE NUMBER OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM

Counting the Pieces Atomic Number = number of protons
# of protons determines kind of atom. the same as the number of electrons in the neutral atom.

Counting the Pieces Mass Number = the number of protons + neutrons.
All the things with mass. NOT on the periodic table

Isotopes Atoms of the same element can have different numbers of neutrons. different mass numbers. called isotopes.

Writing Isotopes Two ways: Hyphen notation
Name of element – mass number Ex: carbon- 12 carbon -14 uranium-235

Nuclear Symbol Notation
Contain the symbol of the element, the mass number and the atomic number. Mass number X Atomic number

Na Symbols 24 11 Find the number of protons number of neutrons
number of electrons Atomic number Mass Number Name 24 Na 11

Na Symbols 24 11 Find the number of protons = 11
number of neutrons = 13 number of electrons = 11 Atomic number = 11 Mass Number = 24 Name = sodium – 24 24 Na 11

Br Symbols 80 35 Find the number of protons number of neutrons
number of electrons Atomic number Mass Number Name 80 Br 35

Br Symbols 80 35 Find the number of protons = 35
number of neutrons = 45 number of electrons = 35 Atomic number = 35 Mass Number = 80 Name = bromine - 80 80 Br 35

Symbols if an element has an atomic number of 34 and a mass number of 78 what is the number of protons number of neutrons number of electrons symbol Name

ANSWERS if an element has an atomic number of 34 and a mass number of 78 what is the number of protons = 34 number of neutrons = 44 number of electrons = 34 Name = selenium – 78 78 Se 34

Symbols if an element has 91 protons and 140 neutrons what is the
Atomic number Mass number number of electrons Name symbol

ANSWERS if an element has 91 protons and 140 neutrons what is the
Atomic number = 91 Mass number = 140 number of electrons = 91 Name = Protactinium - 140 Pa 140 91

Average Atomic Mass A weighted average of all naturally occuring isotopes of an element. There is a formula used to calculate average atomic mass: = (mass of isotope 1) (% abundance/100) (mass of isotope 2) (%abundance/100) +...________________________________

Unit for Atomic Mass The atomic mass unit (amu)
amu definition - one twelfth the mass of a carbon-12 atom. Each isotope has its own atomic mass relative to the carbon-12 atom

Atomic Mass You try… Calculate the atomic mass of copper if copper has two isotopes. 69.1% has a mass of amu and 30.9% has a mass of amu.

Answer (62.93 amu) (69.1% / 100) = amu +(64.93 amu) (30.9% / 100) = amu amu

Atomic Mass Magnesium has three isotopes % magnesium-24 with a mass of amu, 10.00% magnesium-25 with a mass of amu, and 11.01% magnesium-25 with a mass of amu. What is the atomic mass of magnesium?

Answer ( amu) (78.99% / 100) = ( amu) (10.00% / 100) = ( amu) (11.01% / 100) = amu

Atomic Mass Is not a whole number because it is an average.
are the decimal numbers on the periodic table.