Honors Physical Science Midterm AHHHHHHHH!

Independent Variable

Variable that is manipulated by experimenter, does NOT respond to other variables

Energy

The ability to do work

Scientific Method

1. State the problem

2. Develop hypothesis

3. Design an experiment

4. Collect and interpret data

5. State a conclusion

6. Communicate results

Dependent Variable

The variable that changes in response to an independent variable or what’s being measured

Controls of an Experiment

Variable that don’t change

Control Group

Group of variables that don’t get independent variable exposed to them

Experimental Group

Group of variables that are exposed to independent variable

Observation

Gathering of information using our 5 senses (sight, smell, hearing, taste, touch)

Direct and Indirect Observations

Direct: Observing or measuring actual behavior, event, action occurrence, etc that you wish to observe (you directly see it)

Indirect: Involves looking at result or consequence of actual behavior, event, action, occurrence etc you wish to observe

Inference

A judgement based on reasoning from evidence from an observation you made

Density Formula

Density = Mass / Volume

Element

Material made up of only one type of atom

First element to exist in universe, makes up 90% in all atoms today

Hydrogen

Brownian Motion

Perpetual jiggling of particles. The result of collisions between visible particles and invisible atoms

Parts of Atom

Atomic Nucelus: Particle at atom center containing Protons and Neutrons

Nucleus surrounded by electrons(in shells, valence being outermost)

Electrical Repulsion

Atoms can only get so close to neighboring atoms cause like charge

Proton

Positive charge found in nucleus. 2000x larger as massive as electron

Neutron

Same mass as protons, but no electrical charge

Nucleons

Protons and Neutrons since both in Nucleus

Nonmetals

Poor conductors of electricity and heat, can be transparent

• Brittle

• Shattered by Hammer

Metaloids

Both metallic and nonmetallic. 7 elements: Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium

Period and Group of Periodic Table

Period: Horizontal row

Group: Vertical Column

Valence Shell

Outermost shell of the atom

Lewis Dot Structure vs Bhor Model

Lewis Dot shows only electrons on valence shell around atomic symbol

Bhor Model shows all shells and electrons in those shells with nucleus at center

Diatomic Molecule

Molecule composed of only two atoms

Atoms with 3 or few electrons in outer shell tend to…

… lose their electrons so that shell below becomes valence shell (since that shell is full)

Octet Rule

Atoms prefer to have 8 electrons in valence shell

Compounds

A pure substance containing two or more kinds of elements.

• Can’t be separated by physical means

• Always homogeneous

Mixture

Two or more elements or compounds NOT chemically combined

• Can be physically separate

Homogenous vs Heterogenous Mixture

Homogenous Mixture: Uniform mixture which are known as solutions

Heterogeneous Mixture: Non-Uniform mixtures

Physical Vs Chemical Properties

Physical: Usually found using our senses, ex. Color or Density

Chemical: Substances potential ability to change into new substance ex. Reactivity, Combustability

Physical Change

When substance changes phase or other PHYSICAL property, but not it’s chemical composition (doesn’t become new substance) Ex. Melting

Chemical Change

Change in substance involving rearrangement of chemical composition ex. Burning

Exothermic Reaction

Reaction that releases energy to surroundings in form of heat (Exo → Exit)

• When reaction occurs, object raises in temperature

Endothermic Reaction

Reaction that absorbs energy from surroundings (Endo → In)

• When reaction occurs object falls in temperature

Filtration Vs Distillation

Filtration: Seperates solid-liquid mixture using filters (big no go through, small yes go through)

Distillation: Seperates liquids and solids using differences in melting and boiling points

Suspension

Homogenous mixture with components in different phases

Solute vs Solvent

Solvent: Thing which has stuff dissolved in it

Solute: The thing that gets dissolved

Chemical Reaction: Decomposition

Single compound breaks down into two or more simpler substances

Chemical Reaction: Combination

Two or more substances come together as a single compound

Chemical Reaction: Combustion

Result has H2O and CO2

Chemical Reaction: Single Replacement

An element on one side changes into another element on other side (with elements swapping in compounds)

Chemical Reaction: Double Replacement

There’s a compound on one side, and new compound on other side (although trumped by single replacement)

Ionic Bonds vs Covalent Bonds

Ionic: Bonding between metals and nonmetals (give or take relationship)

Covalent: Bonding between nonmetals (sharing relationship)

Ionic Bonding Shortcut

Take ions of other atom, and make that number of this atom

Ex. Be(2) Si(-3) 3Be 2Si

Temperature

Measure of AVERAGE kinetic energy of particles of substance

0 and 100 Degree Celsius

0 - Freezing/Melting Point of Water

100 - Boiling/Condensation point of Water

Formula for Energy Gained Using Specific Heat Capacity

Q = M x C x /\T

Q is Energy gained form transformation (Joules)

M is mass of the substance in grams

C is specific heat capacity of substance

T is change in temperature

Formula for change in Phase

Mass * Heat of Vap/Fus

Conduction vs Convection

Conduction: Movement of heat through direct contact between solids (or liquids)

Convection: Gasses, hot air rising cold air going down

Gravitational Potential Energy Formula

Potential Energy = mass * 9.8m/s² * height

Metal Properties

• Luster/Shiny

• Malleable/flexible as solid

• Conducts heat and electricity well

How to find atomic mass

Add number of protons and neutrons

Cation vs Anion

Cation: Positively charged ion (lost electron)

Anion: Negatively charged ion (gained electrons)

Laws of Thermodynamics

1st: Whenever heat flows into or out of a system, the gain or loss of thermal energy equals heat transferred

2nd: Heat never spontaneously flows from a cold substance to a hot one

3rd: No system can reach absolute zero

System

Any substance or well defined group of atoms, molecules, or objects ex. Steam, dirt, earth’s atmosphere