Download presentation
Presentation is loading. Please wait.
Published byAldous Holland Modified over 9 years ago
1
Chapter 4
2
Smallest part of an element that retains the properties of that element all elements are made of indivisible atoms
3
Two main regions of an atom: I. Nucleus II. Outer Cloud
4
I. Nucleus Most of the atom’s mass Very little space ~1/10,000 th the volume. Contains two subatomic particles Protons (+) Neutrons (0)
5
A. Protons (p + ) Found in the Nucleus Positive Charge Mass is 1 amu Determines the element
6
B. Neutrons (n 0 ) Found in the Nucleus Neutral Charge Mass is the same as a proton Determines nuclear stability
7
II. Outer Cloud Most of the atom’s volume Very little mass Contains Electrons(-)
8
A. Electrons (e - ) Move around the nucleus in concentric shells Negative Charge Very Very Light! Determines Basic Chemical Reactivity
9
Atomic Number The # of Protons Found on the Periodic Table The “Z” Number
10
Atomic Number (must be whole #) Give the atomic number for the following elements: C Be Ca Ar He Cu Fe
11
Mass Number # of particles in the nucleus The “A” number # of Protons + # of Neutrons This is not on the periodic table! Example: A carbon atom has 6 p + and 7 n 0. What is its mass number?
12
Mass Number Give the mass number for the following elements: C: 6 p + and 6 n 0 Be: 4 p + and 3 n 0 Ca: 20 p + and 18 n 0 Ar: 18 p + and 21 n 0 He: 2 p + and 1 n 0 Cu: 29 p + and 34 n 0 Fe: 26 p + and 34 n 0
13
Charge Nucleus = + charge Electrons = - charge (opposites attract) Usually the + and – charges exist in equal number The atom is therefore “neutral”
14
Charge Ion = Charged Atom + charge = cation - charge = anion A Negative ION = ANION
15
Charge Ion’s charge is determined by: p + − e - Example: Nitrogen atom has 7 p + and 10 e - Charge is: -3
16
Charge Find the charge for the following elements: Na: 11 p + and 10 e - O: 8 p + and 10 e - Al: 13 p + and 10 e - Be: 4 p + and 2 e - H: 1 p + and 0 e - Cl: 17 p + and 18 e - Ge: 32 p + and 28 e -
17
Atoms with the same number of protons but different number of neutrons are isotopes. Varied mass due to different numbers of n 0
18
Isotopes Can’t change # of protons That would change the element Can change # of neutrons Compare Carbon sample 1: 6 p + and 6 n 0 Carbon sample 2: 6 p + and 7 n 0 Carbon sample 3: 6 p + and 8 n 0 Which one is the isotope? Answer: They all are!
19
Atomic Mass Weighted Average Based on ALL isotopes of an element This is why it is not a whole number NOT the same thing as mass number
20
Atomic Mass Example: Chlorine has two naturally occurring isotopes: 75% Cl-35 25% Cl-37. Atomic mass of Cl = 35.453 amu
21
Atomic Mass Unit of Atomic Mass = AMU 1 AMU = 1/12 th the mass of Carbon-12
22
How do we indicate what isotope we are talking about? Top Left is for mass number Bottom Left is for atomic number Cl Mass Number Atomic Number
23
What if we had a chlorine atom with 17 protons and 18 neutrons? Mass number = _______ Atomic number = ____________ 35 17 Cl
24
What if we had a magnesium atom with 12 protons and 13 neutrons? Mass number = ____________ Atomic number = _____________ 25 12 Mg
25
Practice: Given the following elements, write the symbol with the mass number and atomic number in the proper locations. C: 6 p + and 6 n 0 Be: 4 p + and 3 n 0 Ca: 20 p + and 18 n 0 Ar: 18 p + and 21 n 0 He: 2 p + and 1 n 0 Cu: 29 p + and 34 n 0 Fe: 26 p + and 34 n 0
26
How else do we indicate isotope? SymbolCl Dash Mass Number35 Cl-35
27
An atom of Carbon has 6 protons and 8 neutrons. C-14
28
How else do we indicate isotope? NameChlorine Dash Mass Number35 Chlorine-35
29
An atom of Hydrogen has 1 proton and 2 neutrons. Hydrogen-3
30
On your worksheet, fill in the appropriate boxes as demonstrated by your instructor.
31
Atomic number = # of protons Mass number = protons + neutrons Not the same thing as atomic mass! Charge = protons - electrons
32
If the # of electrons are changed It becomes an ion If the # of protons are changed It becomes a different element If the # of neutrons are changed It is a different isotope
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.