Physical Science Exam Unit 2

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Propagation

The wave moves in both ways

Wavelength measurement

Space between two Crests or 2 Troughs

Amplitude

Distance between the equillibrium position and the highest point (amount of disturbance)

Types of waves

Sheer waves, compression waves, & Surface waves

Sheer Waves

Moves in right angle (hitting a cymbal) (perpendicular to wave travel)

Surface Waves

Can only travel across the surface of a medium, but like a sheer wave

Compression Waves

Moves left to right
Push and pull molecules in the way of propagation (speaker moving in and out)

Waves

Energy moving from one place to another

What waves do

Reflect
Diffract
Refract
Interference

Diffraction

When a wave bends around a corner (goes through a hole, lights goes through a whole to light up a rooms)

Refraction

Bent light

Constructive interference

Crest

Top of wave

Trough

Bottom of the wave

Wave Speed Equation

Wave speed = Wavelength x Frequency

Standing waves

When waves reflect and interfere with the new waves

Nodes vs. Anti Nodes

Nodes are the points with no movement, anti nodes are troughs and crests

Ambulance Thing

When ambulance is coming towards you → lower wavelength, higher frequency (sounds higher)

When ambulance passes you → Higher wavelength, lower frequency (sounds lower)

A wave where the medium is displaced parallel to the direction the wave travels.

Longitudinal wave

What makes it so light transfers more electrons energy?

Changing the frequency (photons)

Amplitude Determines the total energy of a light wave, and

Frequency determines the individual energy of each photon

Double slit - unobserved

The interference makes vertical lines

Single slit- unobserved

Scatters everywhere but most concentration in the middle

Single slit- observed

Light dots appear where the slit is (light doesn’t refract)

Double slit- observed

Light dots appear where the slits are (light doesn’t refract)

Photoelectric Effect

The ejection of electrons from metals when light is shined on the metal's surface

Pictures teach us about

particles

Carrier wave modulated by changing the frequency

FM

A particle of light. It possesses energy, frequency, and wavelength but neither mass nor charge.

Photon

A series of bright lines separated by dark areas.

Interference Pattern

Carrier wave modulated by changing the amplitude.

AM

Light is an electromagnetic disturbance spread throughout space according to electromagnetic laws.

True

Longest wavelength (lower energy) → Shortest wavelength (highest energy)

ROYGBIV

Sheer Forces

Force that pushes the edges of an object in different directions.

(tearing)

Compression Forces

When something is compressed

Tension Forces

pulling away (opposite directions)

Tension force in a liquid

Sucking liquid up a straw

Electromagnetic Spectrum (highest to lowest)

Gamma

Xray

UV

Visibile Light

Infared

Micro

Radio

(Grandma examines ultra vaccums in my room)

Discrete spectrum

When something only emits a few colors

Conductors

Something that carries a charge, like metalsI

Ionic conductors

Can conduct when it is melted or dissolved (like salt)

A physical state of matter characterized by fluid properties but in which positive and negative charges move independently.

Plasma

Continuous model of matter

You could cut something in half for infinity

Molecular model of matter

Everything is made of molecules
Always in motion (solids vibrate, gases move around more)
Obey fundamental laws

What does the molecular model explain?

Temperature (depends on mass and velocity (KE equation))
Heat flow
Pressure
Density (Solids are moving slower in a smaller space, gases are moving faster in a larger space, so you can fit less)

Rutherford’s Model (solar system)

All the positively charged particles are condensed in the nucleus, so dense it can take a blow. Electrons then orbit around the nucleus

Alpha particles

Positively charged particles

Issue with the solar system model

When viewed, atoms show discrete spectrum, not a continuous one.

Modified Solar System Model

Nucleus surrounded by energy levels (lowest to highest)

Electron orbits around on the lowest level, has to gain energy to move levels

Wavelength Equation

Lambda = Planks Constant/Momentum

Heisenburgs uncertainty principle

If we know the momentum of a particle, we can’t know much about the position and vise versa

Quantum Atomic Model

Map the probability of where electrons are

Issue with the modified solar system model

Electrons aren’t supposed to be accelerating

Different types of orbitals

Periodic table based on orbitals

Period Table Directions

Ionization energy increases slightly from the bottom to top of a group and much more from the bottom left to the top right.

Atomic size increases from top right to bottom left (NOT MASS)

Ionization energy

Energy required to strip an atom of its valence electrons

Valence electron

Electrons that are in the outermost shell

Elements that occur in the same row of the Periodic Table.

Period

A kind of matter that contains atoms that all have the same number of protons in their nuclei.

Element

Elements in the periodic table which are placed in the same column and have similar chemical properties.

Family

How do I know the number of valence electrons that an element has?

Based on the last digit of the group number

Elements with atomic numbers heavier than 92 (uranium) are all man-made elements.

True

Within a given period, metals have higher ionization energies than non-metals do.

False

How to tell the density of things from a periodic table

Density = M/V

If they all have similar volumes, the atomic mass that’s biggest will be the most dense
Mass gets bigger going from top-right to bottom-left

On which side of the periodic table are non-metals found?

Right

Why do elements in the same column of the periodic table react in similar ways?

 Each element in the column has the same number of valence electrons.

What determines if an element is likely to give away an electron

How high the ionization is