1. Physical Science – Grade 8
Chapters 10,11,12,18, 19

2. Structure of the Atom
Matter- anything that takes up space and has mass
Matter also has inertia
Atoms are the smallest units of matter

3. Subatomic Particles
Atoms consist of a positively charged center, or nucleus, surrounded by negatively charged particles called electrons .
The two major kinds of particles in the nucleus are protons and neutrons.
Protons are positively charged particles.
Neutrons carry no charge.

4. Masses of subatomic particles
Subatomic particle/ charge
Mass
Proton
positive charge (+)
Neutron
Neutral (0 charge)
Electron
Negative charge (-)
1 atomic mass unit (u)
negligible

5. Model of the Atom
In this model, electrons move around the nucleus in a region called the electron cloud.
What two subatomic particles are in the nucleus? What are their charges and masses?

6. Electrons and Their Energy Levels
Energy Level of Atom
Maximum Number of Electrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32

8. Elements and Atomic Number
Element – A substance made up of only one type of atom
The atomic number for each element is the number of protons.
The number of protons are = to the number of electrons (in a neutral atom)

9. Atomic mass – Atomic number = Number of Neutrons in the atom
The Mass of an Atom
Protons + Neutrons = the Atomic Mass of the atom
Isotopes – atoms of the same element with different numbers of neutrons
The average atomic mass of an element is the average mass of the mixture of its isotopes
Atomic mass – Atomic number = Number of Neutrons in the atom

10. The Periodic Table
Elements are arranged according to increasing atomic number
A Chemical Symbol is a shorthand way of writing the name of the element.

11. The Periodic Table (continued)
Vertical columns are called Groups (1-18)
Group 18 elements are known as Noble Gases
Horizontal rows are called Periods (1– 7)

12. Metals, Metalloids & Nonmetals

13. Elements and their Properties
Chapter 12
Elements and their Properties

14. Metals & Nonmetals Metals Nonmetals Located on the left side
of the periodic table
Located on the right side
Metallic Luster
(Shiny)
Dull
Malleable
(can be hammered and shaped)
Brittle
Ductile
(can be made into a wire)
Non-ductile
Solid (except for Mercury, which is room temperature)
Gases (except for Bromine, which is room temperature)
High Melting Point
Low Melting Point
Fewer than 3 Electrons
in Outer Energy Level
More than 4 Electrons

15. Coinage Metals
Copper Silver Gold
(Group 11)

16. Magnetic Metals Iron Cobalt Nickel (Period 4) Fun Fact:
Did you know that the Canadian nickel can be magnetized?
(The American nickel cannot)

17. Metalloids
Metalloids are located on the staircase between metals & nonmetals.
Metalloids have properties of both metals and nonmetals.
Ex: Silicon has a metallic luster and is brittle
Boron
Silicon
Germanium
Arsenic
Antimony
Tellurium
Polonium

18. Chapter 11 Chemical Bonds

19. Compounds A compound is two or more elements chemically combined.
Compounds take on properties that are different than the elements that they consist of.
The compound sodium chloride (salt)
consists of the elements sodium & chlorine.
Na + Cl  Sodium Chloride

20. Chemical Formulas A Chemical Formula is a shorthand for the compounds.
Subscript: Number “Written Below” that tells how many atoms of that element are present in the compound
1. How many atoms of Hydrogen are present in this chemical formula?
2. How many atoms of Oxygen are present?

21. Question
Answer
Why do elements form compounds?
They want to become chemically stable.
What is a chemically stable atom?
For the atoms of most elements,
the outer energy level is completely filled with 8 electrons.
Which elements are most stable?
The noble gases, because their outer energy levels are full.
Are there any exceptions to the Rule of 8?
Yes! Helium!
(Helium has 2 electrons,
but it only has 1 energy level)

22. Kinds of Chemical Bonds
A chemical bond is a force that holds together the atoms in a substance.
IONIC
COVALENT
Formed by the transfer of electrons
Produces Ions
Formed by the sharing of electrons
Ion-
an atom with either a positive or negative charge
Molecule-
smallest part of a covalent compound

23. CHAPTER 18
WAVES AND SOUND

24. CHARACTERISTICS OF WAVES
Waves- are rhythmic disturbances that carry energy through matter or space
Medium- A material through which a wave transfers energy

25. Parts of a transverse wave
Transverse Waves
Transverse Waves – The medium moves at right angles to the direction the wave travels
Parts of a transverse wave
Crest – The highest point in a wave
Trough- the lowest point in a wave
Wavelength - the distance from one successive crest to crest or trough to trough
Amplitude – the distance from the rest position to the crest or the rest position to the trough

26. Measuring Transverse Waves
Frequency – is the number of wave crests that pass one place each second
Frequency is measured in Hertz (Hz)
Wave Velocity- how fast a wave moves forward
velocity = wavelength x frequency
V = x F

27. DIAGRAM OF A TRANSVERSE WAVE
Equilibrium position = Rest Position

28. Compressional Waves
Compressional Wave – matter vibrates in the same direction as the wave travels
Sound travels in compressional waves
A compressional wave is composed of a compression and rarefaction

29. Comparing Transverse & Compression Waves
WAVELENGTH
Crest to Crest OR
Trough to Trough
1 compression +
1 rarefaction
FREQUENCY
# of crests that pass a point in 1 second
# of compressions that pass a point in seconds
AMPLITUDE
Height
(distance from rest position to crest or to trough)
Amount of Compression
VELOCITY
V = x F
V = x F

30. Comparing Transverse & Compressional Waves

31. Moving Through Media The speed of sound waves depends on 2 things:
Medium through which waves travel
Temperature of the medium
*Types of Media:
solids, liquids (best conductors of sound)
gases
Speed of Sound = 761 m/h
Speed of Light = 186,000 m/s
Which one do you think travels faster?

32. Using Sound Waves! Ultrasonic (above 20,000 Hz)
high-frequency waves
Used in sonar (sound navigation ranging)
Medical uses
Infrasonic (below 20 Hz)
Heavy machinery
Thunder
Body rumblings

33. Bats can detect sounds as high as 100,000 Hz
Fun Fact
Bats can detect sounds as high as 100,000 Hz

34. Decibel Scale Loudness is the human perception of sound intensity.
The intensity level of a sound is measured in units called decibels (dB).
Sounds with an intensity level about 120 dB may cause pain & permanent hearing loss.

35. Why does the sound have a lower pitch after the vehicle has passed?
The Doppler Effect is defined as the change in frequency & pitch of a sound as a result of motion.
The pitch of the emergency vehicle’s siren is higher when the vehicle is approaching because the wave crests are closer together.
Why does the sound have a lower pitch after the vehicle has passed?

36. Music to Your Ears
Music- created using specific pitches- sound quality followed by a regular pattern Noise- no set pattern, no definite pitch

37. Music… Continued
Resonance- the vibrating of an object at its natural frequency
Sound Quality- the difference among sounds of the same pitch and loudness
Interference- ability of 2 or more waves to combine and form a new wave
Reverberation- many reflections of a sound
Acoustics- the study of sound

38. Chapter 19 - LIGHT

39. Electromagnetic Radiation
Electromagnetic Waves are transverse waves produced by the motion of electrically charged particles
Electromagnetic Radiation is the transfer of energy by electromagnetic waves.
- These can travel through a medium
- These waves can also travel through a vacuum at 300,000 km/s (186,000 m/s)

40. Electromagnetic Spectrum
Electromagnetic Spectrum- the arrangement of waves according to wavelength & frequency
Photons- tiny, particle-like bundles of radiation

42. Types of Radiation RADIATION USES Radio Waves
Communication, TV, phone, medicine
Micro Waves
Type of Radio Wave used in cooking
Infrared Waves
Military, Police, Medicine, Heat Detection
Visible Radiation (Visible Light)
Allows the human perception of objects
Ultraviolet Waves
Enables Skin Cells to Produce Vitamin D, Kills Bacteria, Tanning Salons (despite negative effects)
X-Rays
Medicine
Gamma Waves
Cancer Treatment
Gamma Waves have the highest frequency and are the most penetrating.
They can cause cancer and they can cure cancer.

44. how popcorn kernels pop so quickly in the microwave???
Do you ever wonder….
how popcorn kernels pop so quickly in the microwave???

45. Light & Matter Opaque Transparent Translucent Type of Material
Properties
Opaque
Allows no light to pass through
Transparent
Allows all light to pass through
Translucent
Allows some light to pass through

46. White = reflection of all colors Black = absorption of all colors
Why does grass appear green?
Why is the sky blue?
The color that you see is the wavelength of the colors that are reflected to your eye.
The remainder of the colors are absorbed by the object.
White = reflection of all colors
Black = absorption of all colors

47. Kinds of Lighting Incandescent Bulbs Fluorescent Bulbs
Produces a lot of heat
Contains tungsten filament
Produces light without excessive heat
Contains argon gas
Green Fact:
The country is now turning over to LED Lighting, due to less energy use and more brightness.

48. Properties of Light REFLECTION REFRACTION DIFFRACTION
Bouncing of light waves
Bending of light waves
Bending of waves around a barrier