science lt 1 final atomic anatomy, laws of motion, fundamental forces

8/3/2019 Science LT 1 FINAL Atomic Anatomy, Laws of Motion, Fundamental Forces

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Atomic Anatomy

- an atom has 3 basic particles: 1. Proton (nucleus), 2. Neutron (nucleus), and 3. Electron (outside the

nucleus)

- atomic number = # of protons = * # of electrons (* if atom is neutral)

- most atoms are neutral (+ = -), but some atoms gain or lose an electron. When this happens, the atombecomes charged; ION

Ex: Fluorine atom + 1 electron F-

Sodium atom 1 electron Na +

- mass number = # of protons + # of neutrons

- # of neutrons = Mass number Atomic number

Element Atomic # Mass # # of Protons # of Electrons # of Neutrons

Hydrogen 1 1 1 1 0Carbon 6 12 6 6 6

Oxygen 8 16 8 8 8

* atomic number determines the type of element

Isotopes

- atoms of an element with different number of neutrons AND different masses

Ex: Hydrogen 1 (protium) 1 proton, 0 neutronsHydrogen 2 (deuterium) 1 proton, 1 neutron

Hydrogen 3 (tritium) 1 proton, 2 neutrons

* neutron = 1.009 amu electron = 0.0005 proton = 1.007 amu

- unstable atoms/isotopes are radioactive: their nuclei decay (nuclear decay)

- uses of Isotopes: Bone scans, Medicine (Chromium, Iodine, etc.)

Ions

* cations positive ions (protons > electrons)

anions negative ions (protons < electrons)

* only electrons can transfer from one atom to another. Ionic compounds are formed by cations and

anions.

Ex: O-2

x = number of protons, x + 2 = number of electrons

- when an atom loses or gains an electron, it becomes charged; IONS


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Atomic Mass

[ (% abundance of isotope) (mass of isotope) + (% abundance of isotope)

(mass of isotope) + ]

Ex: Chlorine. Give the abundance of Chlorines Isotopes.

Given: Cl35

34.969 amu, Cl37

36.966 amu, Atomic Mass = 35.453 amu

35.453 = [ (x) (34.969) + (1-x) (36.966) ]

35.453 = 34.969x + 36.966 36.966x

36.966 35.453 = 36.966x 34.969x

1.513 = 1.997x

X = 1.513 / 1.997

X = 0.7576364* Sig. Figs!

X = 75.76%, 1-X = 24.24%

Cl35

s abundance is 75.76% while Cl37

s abundance is 24.24%.

Laws of Motion

Force

- push or pull exerted on an object

- can move objects

- can stop the motion of an object

- can change the direction of motion

- can change the shape or form of an object

- Sl Unit Newton (N)

Some terms Sir mentioned:

- elastic limit

- yield strength

- normal force (cancels out the gravitational force)

* an object will not change its motion by itself, an external force is required to cause this change. Unless

it is in motion with constant velocity

Aristotle

- scientist from Ancient Greece

- believed that, except for heavenly bodies, the natural state of things was a state of rest, a force was

required to keep objects in motion.


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Galileo Galilei

- scientist from Italy

- inferred that, an object in motion would tend to keep on moving if there was no retarding force

acting on it.

- gave the term Inertia to this tendency of an object to keep moving

- was able to see what would happen in the absence of friction

Isaac Newton

- picked up where Galileo left of

- formulated 3 Laws of Motion: Inertia, Acceleration, and Action-Reaction

Newtons 1st

Law of Motion: Law ofInertia

- refinement of Galileos ideas

- An object at rest tends to remain at rest. If in motion, it will tend to move at constant speed in a

straight line unless it is acted upon by an unbalanced external force.

* an objects mass is a measure of its Inertia

- m = Inertia, m = Inertia- hefting shaking two objects to see which is heavier

*Inertia is the property of an object to resist changes in itsstate of motion or rest

* Net Force = 0

if at rest, V=0

if in motion, at constant velocity

Newtons 2nd

Law of Motion: Law of Acceleration

- An objects acceleration is directly proportional to the Net Force acting on it and is inversely

proportional to the objects mass. The object always accelerates in the direction of the Net Force.

* F = ma

F Net Force in N, m Mass in kg, a Acceleration in m/s2

- F = A, F = A, M = A, M = A

Newtons 3rd

Law of Motion: Law ofInteraction/Action-Reaction

- For every action, there is an equal and opposite reaction.

- forces in Nature always come in pairs

- action-reaction forces act on different objects


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Force- Can make objects move, speed up, slow down, or simply change its direction- A push or a pull

Objects that are not in motion doesnt necessarily mean they are not acted upon by forces. For

stationary objects, the forces are balanced, so there is no motion.

Contact Forces

- Exerted between objects that are in close contact.Examples: Friction, Force that makes huge ships float, Force that enables airplanes to fly

Noncontact Forces- Exerted between objects that arent even touchingExamples: Gravity, Magnetism, Strong Force, Weak Force

The Fundamental ForcesGravitational Force

- Formulated by Isaac Newton- Affects anything that has mass- An attraction, or pull between objects- The strength of the force depends on the masses of the objects and their separation- Always attractive

Dependence on Mass- Ones weight is just our planets gravitational force on that him- If ones mass changes, his weight changes as well- Any attraction (gravitational) between you is negligible. If one gets close enough to a really large

mass (like a planet), you will get stuck to it

Dependence on Distance- The closer two objects are, the greater the gravitational force is. But as the separation

decreases, the gravitational force quickly decreases

- There are billions of objects in our universe that are more massive than our own planet, but dueto their immense distance, the force they exert on us is negligible

Electromagnetic Force- Electric and magnetic forces are very closely related and are unified into one force, the

electromagnetic force

- For charged objects, the rule is that like charges (both positive ot both negative) repel, andunlike changes (positive and negative) attract

- This force can be more than a billion times stronger than gravity. It is dependent on the amountof charge possessed by objects. It also shows a dependence on distance. But unlike gravity, this

force can be either repulsive or attractive

Examples: Plastic comb attracting your hair, Electrons revolving around the nucleus

y We never touch anything. We merely experience electromagnetic forces of repulsionWeak Force


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- Not the weakest of the four fundamental forces. Its actually stronger than gravity.- Only active at distances less than 10-18- Exerted between a class of particles called leptons and hadrons- An electron is an example of a lepton, and the proton and neutron are examples of hadrons- Tends to cause nuclei and elementary particles to break up or became unstable; beta decay

Strong Force

- Strongest of all fundamental forces- Only effective at very short distances (10 -25)- At great distances, this force is negligible- Without this force, the protons would quickly fly apart and the atom would disintegratey It takes a tremendous force to overcome the strong force. But if it is overcomes, it results in the

splitting of nuclei to form lighter nuclei. This process, known as nuclear fission, releases

tremendous amounts of energy. This is what causes the immense power of the atomic bomb.

science lt 1 final atomic anatomy, laws of motion, fundamental forces

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