Science

Chewing food to break it down into smaller particles represents a _____ change, but the changing of starch into sugars by enzymes in the digestive system represents a _____ change.

1.) physical change because no new substance was formed 2.)chemical, because starch turns into sugar(forms a new substance) and takes in heat(feels warm)

8 indicators that a chemical change/reaction has occurred.

1.)Gives off heat (feels cold to touch) / takes in heat (feels warm to touch) 2.)Forms a gas (bubbles) 3.)Gives off light 4.)Gives off odor 5.)Change in color 6.)Can't be undone 7.)Forms a solid (precipitate) ****8.) the formation of a new substance****

Examples of chemical change

1.)silver tarnishing 2.) Baking soda reacting to vinegar 3.) Iron rusting 4.) Milk turning sour 5.) Wood rotting 6.) Pancakes cooking 7.) Digesting food

Examples of physical change

1.)table salt dissolving in water 2.)Cutting an apple into pieces 3.) Heat changing H2O to steam 4.)Alcohol evaporating 5.) Ice melting 6.)Sugar dissolving in water 7.) Grass growing 8.)A tire being inflated

chemical change

A change that occurs when the atoms that make up two or more substances are rearranged to form a new substance.

Compound

A new substance with unique chemical and physical properties formed when two or more elements are chemically bonded during a chemical reaction

Product

A substance produced during a chemical reaction

Reactant

A substance that takes part in and undergoes change during a reaction

Magnesium is a shiny, flexible metal that can be burned in the presence of air. When it is burned, it produces a white powder that is no longer shiny nor flexible. This white powder also has more mass than the original magnesium which is the best evidence that a chemical reaction has occurred a.) A new substance has formed b.) the mass of the magnesium changed c.) the molecules were separated into individual atoms d.) smoke that was trapped between the magnesium atoms was given off

A, because the formation of a new substance is an indicator of a chemical reaction

Copper Sulfate,when dissolved in water, has a blue color. When steel wool is mixed with a copper sulfate solution, the steel wool disappears, a brownish solid forms, and the color of the substance changes from blue to green which is the best evidence on why this is a chemical reaction? a.) the color changed from blue to green happens in nature b.) the disappearance of the steel wool shows that a new substance has formed c.) Energy is lost in this reaction like all other reactions d.) The solid precipitate is a waste product in the reaction

D, because waste products cannot exist without a chemical reaction it's not B because just because something disappears doesn't mean a new substance will form( water evaporates it only changes it's state of matter)

Chemical process

Method or means of changing one or more chemicals or chemical compounds

Synthetic Materials

Natural resources that undergo a chemical process

why is it when you cut an apple it turns brown?

Once you cut into an apple you are opening up some of the cells inside it. Those cells react to the oxygen in the air and start to turn the apple brown.

What is the difference between Physical and chemical properties

PHYSICAL PROPERTIES -observed with senses - determined without changing the substance CHEMICAL PROPERTIES - Indicates how a substance reacts to something new - matter will change into a new substance after the reaction

properties

Physical and chemical characteristics of matter used to describe or identify a substance.

" A student removes a loaf of bread hot from the oven. The student cuts a slice off the loaf and spreads butter on it" is an example of what type of change and why?

Physical change, because no new substance was formed compared to if the student did something like burn the bread

REASONING

Start with definition, Restate your claim,Summarize your evidence, and finally, Reword claim for conclusion sentence

Combustion

The act or process of burning something requires fuel, heat, oxygen(heat in our homes, fuel in our cars)

Endothermic

a reaction or process accompanied by or requiring the absorption of heat by it's surroundings Ex:the melting and evaporation of water

Exothermic

a reaction or process accompanied by the release of heat Ex: burning coal

Precipitate

a solid is deposited from a solution

Catalyst

a substance that increases the rate of a chemical reaction without itself undergoing any change, Ex: Enzymes are a catalyst in the human body that speeds up cellular activity

indicators of physical properties

color,density,5 senses,solubility

indicators of chemical properties

flammability,combustion and reaction to water,air,acid

can you identify a chemical based solely on its physical properties?

no, when physical properties are similar, you can use chemical reactions(chemical properties) to help identify the substance

CLAIM

one sentence answer to the question.

Jared left a metal truck outside for a week when he went on vacation with his family. When he got back, he noticed that some of the metal changed into a reddish, flaky substance. He didn't know why this happened, so he decided to do some research.

oxidation had caused his truck to rust. rust or iron oxide (iron + oxygen ) forms when iron(a type of metal) meets oxygen in air or water. Iron loses electrons causing the metal to breakdown and rust. his truck was made out of steel which is made out of iron. Salt in the ocean and air with moisture(humidity) will speed up the oxidation process.

Oxidation

the process or result of oxidizing or being oxidized, getting oxygen Ex: Rusting, Apple turning brown after being cut

Molecule

the simplest unit of a chemical compound that can exist, formed when two or more atoms join together chemically

Atom

the smallest particle of an element, made of electrons,protons, and neutrons