Science final - 9th grade - Semester 1

6 parts of the scientific method

1. ask a question or state a problem

2. gather information

3. construct a hypothesis (claim)

4. test your hypothesis (conduct the experiment)

5. analyze data (evidence)

6. draw a conclusion (reasoning)

Hyphothesis

if-then-because statementco

control group

most normal state

experimental group

the groups that are receiving the change or basically not the normal one

independent variable

the variable that is being purposely changed or manipulated

dependent variable

the variable that is being observed

constant variables

variables that are kept the same throughout the experiment

scientific model

representation of an object or event

scientific law

a statement that summarizes a pattern found in nature

scientific theory

an explanation of things from the natural world that’s widely believed as true

bar graph

pretty much good for everything

pie charts

good for parts of a whole or percentages

line graph

good for things shown over time

which variable is on which axis

independent: X axis

dependent: Y axis

Who uses the metric system:

pretty much everyone except the US

Why is the metric system preferred in the US for things like science and medecine

because it’s consistent, simple, precise, it ensures less errors because there’s no conversion necessary, and it ensures that scientists globally speak the same “language”

units and prefixes in the metric system

mili- thousandth

centi- hundredth

deci- tenth

deka- tens

hecto- hundreds

kilo- thousands

origin science vs operational science

Operational science is focused on testable, repeatable, and observable things with controlled experiments and testing hypotheses while Origin science focuses on unrepeatable past events like origin of life or species with things like studying DNA, fossils, or rock layers. 

precision vs accuracy

Precision is a gauge of how exact a measure is over and over again, accuracy is the closeness of a measurement to the actual value of what is being measured or to the exact value. (Example: a clock that says 9:23 and 45 seconds is precise but if it’s the completely wrong time then it’s not accurate, a clock that says 8:30 is less precise because it doesn’t say seconds but it’s very accurate because it is 8:30)

Lab safety

1. wear goggles

2. hair up

3. no horseplay

4. no running

5. no distractions (food, computers, drinks)

Mixture

a combination of two or more elements that is not chemically bonded

solution

When substances dissolve and form a homogeneous mixture (salt water)

suspension

a heterogeneous mixture that separates into layers over time (muddy water)

elements

Pure substance made up of one atom and cannot be broken down

compounds

 Two or more elements chemically bonded.

chemical properties

a property’s ability to undergo changes that change the substance (rust, flammability, reactivity to acid)

physical properties

Characteristics that you can observe/test. (volume mass, color, odor, boiling/melting point)

chemical changes definition

A composition change creating a new permanent substance.

signs of a chemical change

A new color, temperature change, new smell, gas produced, precipitate formed.

physical changes definition

Composition of substance does not change, changes characteristics not permanently. 

phase changes

Freezing (solid), Melting (liquid), Boiling (gas)

states of matter and phase changes

Solid (particles close together in a defined shape and volume with little movement), Liquid (Some space between particles, moving farther and faster than solids), Gas (Lots of space between particles, move very fast, no definite volume or shape.)

kinetic theory of matter

Everything is made up of particles in constant motion.

what effects gas pressure

Temperature, volume, and number of particles.

what happens to a substance during a change of temperature

as a substance becomes cooler, particles slow down and once they hit 0 celsius they set into a shape (freezing) and particles move very slowly. As a substance becomes warmer particles move faster and more freely, creating less and less of a solid set shape (melting) until it no longer has a defined shape (gas) and moves very quickly.

How does pressure, volume, number of gas particles, and temperature relate to each other

pressure & temperature - if pressure increases then temperature increases (gay-lussacs) temperature & volume - If temperature increases then volume will increase (charles) volume & pressure - if volume increases then pressure decreases

boyle’s law

pressure₁ x  volume₁ = pressure₂ x  volume₂ (pressure and volume)

charles’ law

volume₁/temperature₁= volume₂/temperature₂ (volume and temperature)

gay-lussac’s law

pressure₁/temperature₁=pressure₂/temperature₂ (pressure and temperature)

Describe how the atomic model has changed over time and ???how different scientists contributed to the model???

Originally Greeks believed that atoms were tiny spheres with textures corresponding to texture of the larger object, later we realized that that’s not true and that atoms are made up of positive, negative and neutral parts and even later we discovered where the protons, neutrons and electrons were located in the atom.

Identify ways the periodic table is organized

periods are rows, groups are columns and the table is increasing from left to right and down the rows.

Describe the role of protons, neutrons, and electrons in an atom

 protons have a positive charge, are in the nucleus of the atom, have a mass of one, and it determines the element.

Neutrons have a neutral charge, are in the nucleus of the atom, have a mass of one, and stabilize the nucleus.

Electrons have a negative charge, have a mass of zero, and it determines the charge.

Atomic Number

how many protons and electrons and what element it is. 

atomic mass

mass of the element and it’s protons + neutrons

isotope

to find an isotope when comparing 1 atom to the table then look and if the charge is zero and its mass doesn’t match the mass on the table then it’s an isotope.

If you're comparing 2 atoms then it’s if the neutrons are different then it’s an isotope.

Ion

When comparing 1 atom to the table if it has a negative or positive charge then it’s an ion.

When comparing 2 atoms it’s if the protons and electrons are not equal from one atom to the atom.

electron shells

another name for rings

valence electrons

electrons in the farthest outside ring or shell

Use a periodic table to distinguish between metals and nonmetals

metals are to the bottom left of the divider line and metals are to the top right of the divider line.

determine the types of bonding

non-metal and metal is ionic, non-metal and non-metal is covalent. 

Explain what the Octet Rule is and how it fits into bonding

most atoms need 8 valence electrons to be stable so we use different methods to share/give/take VE to get the atoms to where they need to be.