Chemical/physical changes/metals

ALL Elements and ALL Compounds are

• able to be broken down

• Chemical Formulas

• Chemical Symbols

• Pure Substances

Answer explanation

Elements and compounds are pure substances because each is composed (made of) of one type of atom for elements (pure) and one type of molecule for compounds such as H20 (water) or NaCl (Salt)--pure salt or pure water.

Choose the BEST and COMPLETE Answer to describe What an Element is.

• Made of one type of atom and a pure substance

• Made of one type of atom and cannot be broken down

• Made of one type of atom, pure substance, cannot be broken down, is represented by a chemical Symbol on the Periodic Table of Elements.

• Made of one type of atom and is a pure substance and is shown on the Periodic Table of Elements.

Which answer is the BEST. All are partly correct. The question is what are the characteristics of a compound?

• Compounds are pure substances.

• Compounds are pure substances and can be broken down. Compounds are shown on the Periodic Table of Elements.

• Compounds CAN be broken down, are composed of two or more elements, are NOT SHOWN on the Periodic Table of Elements, are represented by a Chemical Formula and are Pure substances.

• Compounds are the same as elements in that both can be broken down.

Tags

NGSS.MS-PS1-1

Chemical changes show the following--choose the MOST COMPLETE ANSWER.

• Form a new substance, cannot be reversed, mass of the object will decrease.

• Form a new substance, cannot be reversed, mass of the object will decrease, energy change will be large.

• Form a new substance, cannot be reversed, mass of the object will increase, energy change will be small.

• Form a new substance, cannot be reversed, mass of the object will decrease, energy change will be small.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Differences between a chemical change and a physical change are

• The amount of mass left after a chemical change is smaller. The amount of mass left after a physical change remains the same.

• The amount of mass left after a chemical change is smaller than after a physical change AND a chemical change the energy change is large.

• A physical change is cutting, bending, tearing and a Chemical change could involve fire, high temperatures, or color changes or a new smell.

• All of the above answers are true.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Do we eat and breath some elements, compounds, and chemical changes?

• Yes, because we eat cookies, salt, and breathe oxygen and drink H20. O is an element and cookies, salt, and H20 are compounds.

• No, we do not eat these things.

• Yes, because we eat chemicals and elements and compounds are chemicals.

• The correct choice is both number 1 and number 3.

Tags

NGSS.MS-LS1-7

What are the most common Elements found on Earth?

• O, H, Mg, Si

• O, C, H, N

• H, C, H20 and SALT

• H20, S, N

Tags

NGSS.MS-PS1-1

What are all the ways a physical change can occur?

• Freezing, steam, evaporation, change shape, bending, crushing, chopping, melting, drying clothes, eating metal

• A New Substance forms

• Mass decreases, new substance formed, chopping, evaporating

• None of these show evidence of a physical change

Tags

NGSS.MS-PS1-4

Which choice shows evidence of a chemical change occuring?

• Mass is decreased, chopping

• Mass is decreased, new substance formed, large expenditure of energy, irreversible, gas bubbles, color change, smell.

• Chopping, evaporating, cutting, crunching, bending, tearing, freezing, melting, steam rising.

• None of these show evidence of Chemical Changes

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which is represented by a Chemical Symbol--compounds or elements?

• Compounds

• Both Compounds and Elements

• Only Elements

• Mixtures