Module 1 _ Gears 2

What does the Atomic Theory state about matter?

• Matter is made of energy waves.

• Matter is made of tiny particles called atoms.

• Matter is made of large particles called molecules.

• Matter is made of invisible forces.

Answer explanation

The Atomic Theory states that matter is composed of tiny particles called atoms, which are the fundamental building blocks of all substances. This distinguishes it from other options that incorrectly describe matter.

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NGSS.MS-PS1-1

NGSS.MS-PS1-5

How have scientists improved their understanding of the atom over time?

• By ignoring previous models.

• By developing new models as technology improved.

• By using only ancient theories.

• By focusing solely on chemical reactions.

Answer explanation

Scientists have improved their understanding of the atom by developing new models as technology advanced, allowing for more accurate representations and insights, rather than ignoring past models or relying solely on ancient theories.

What are the charges and locations of protons and neutrons in an atom?

• Protons are neutral and found in the electron cloud; neutrons are positive and found in the nucleus.

• Protons are positive and found in the nucleus; neutrons are neutral and found in the nucleus.

• Protons are negative and found in the nucleus; neutrons are positive and found in the electron cloud.

• Protons are positive and found in the electron cloud; neutrons are neutral and found in the electron cloud.

Answer explanation

Protons are positively charged and located in the nucleus of an atom, while neutrons are neutral and also found in the nucleus. This makes the second answer choice correct.

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NGSS.MS-PS1-1

Which subatomic particle has a negative charge and is found outside the nucleus?

• Proton

• Neutron

• Electron

• Atom

Answer explanation

The electron is the subatomic particle that carries a negative charge and is located outside the nucleus of an atom, unlike protons and neutrons, which are found within the nucleus.

Tags

NGSS.MS-PS1-1

What is the relative mass of a neutron?

• 0 amu

• 1 amu

• 2 amu

• 3 amu

Answer explanation

A neutron has a relative mass of approximately 1 atomic mass unit (amu). This is the standard value used in atomic physics to represent the mass of neutrons, making '1 amu' the correct choice.

How are elements organized in the periodic table?

• By atomic mass

• By atomic number

• By density

• By melting point

Answer explanation

Elements in the periodic table are organized by atomic number, which is the number of protons in an atom's nucleus. This arrangement reflects the periodic law, where elements with similar properties appear at regular intervals.

What do periods in the periodic table represent?

• Vertical columns with similar properties

• Horizontal rows with increasing atomic number

• Groups of metals

• Elements with the same atomic mass

Answer explanation

Periods in the periodic table are horizontal rows that indicate elements arranged by increasing atomic number. Each period represents a new electron shell being filled, distinguishing them from vertical columns, which are groups.

Which of the following is a chemical property of matter?

• Density

• Color

• Flammability

• Melting point

Answer explanation

Flammability is a chemical property because it describes how a substance reacts with fire, indicating its ability to combust. In contrast, density, color, and melting point are physical properties.

What is the formula for calculating density?

• Density = Mass × Volume

• Density = Mass ÷ Volume

• Density = Volume ÷ Mass

• Density = Mass + Volume

Answer explanation

The correct formula for calculating density is Density = Mass ÷ Volume. This means that density is determined by dividing the mass of an object by its volume, which is essential for understanding material properties.

Why can density be used to identify substances?

• Because it changes with the amount

• Because it is the same regardless of the amount

• Because it is different for each sample

• Because it is only applicable to liquids

Answer explanation

Density is a characteristic property of a substance that remains constant regardless of the amount present. This consistency allows it to be used effectively to identify different substances.