Unit 3 Study Guide: Atoms & Periodic Table

Unit 3 Study Guide: Atoms, Periodic Table, & Density

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The Atom

An atom is defined as the smallest particle of a substance that can exist by itself or be combined with other atoms to form a molecule.

Nucleus of the Atom

Nucleus is located at the center of atom.

Almost whole mass of atom is concentrated in its nucleus. Nucleus itself consists of two kinds of particles, protons and neutrons.

Multiple Select

The nucleus of an atom is made of what parts? (multiple answers)

• electrons

• isotopes

• protons

• neutrons

Protons

• Protons are positively charged particles.

• The number of protons in nucleus of an atom represents the atomic number of atom.

Neutrons

• Neutrons do not have any electrical charge.

• Neutrons are neutral.

• Neutrons are in the nucleus.

Multiple Choice

Neutrons have a negative charge.

• true

• false

Electrons

• An electron is a negatively charged particle.

• The electrons revolve around the nucleus in shells (also called orbits).

• The electrons revolve in a part of the atom called the electron cloud.

Multiple Select

Check all of the correct answers. Electrons are:

• negatively charged.

• in the nucleus.

• orbiting the nucleus.

• positively charged.

Atomic Mass

Atomic mass is the mass of the nucleus. Atomic mass is the total of the protons plus the neutrons.

Atomic Mass

Atomic mass= protons + neutrons

If you have one part of the equation, you can find the other.

How many neutrons?

atomic mass=protons+neutrons

28.086=14 protons + HOW MANY NEUTRONS?

28.086-14= 14.086 neutrons

(We round to 14)

Valence Electrons

Valence electrons are the electrons of the last energy level. They are on the outermost shell of the atom. They decide an atom's reactivity.

Is it happy and full or is it looking for another atom to be complete?

How to Identify an Element

If you know the atomic number of an element, you can find it on the periodic table.

What element has an atomic number of 79?

Multiple Choice

Which element has an atomic number of 6?

• hydrogen

• carbon

• nitrogen

• oxygen

Multiple Choice

Which element has 6 protons?

• hydrogen

• carbon

• nitrogen

• oxygen

Multiple Choice

Carbon has 6 protons.

Carbon has an atomic number of 6.

Atomic number=number of protons

• true

• false

How is the periodic table organized?

It is separated into the categories metals, metalloids, and nonmetals.

Multiple Select

The periodic table is made up of...

Select all that apply.

• metals

• metalloids

• oxides

• non-metals.

Characteristics of Metals

• shiny (luster)

• malleable (can be hammered into thin sheets)

• good conductors of electricity

• ductile (can be used in wires)

•  solid at room temperature

• Left side of periodic table (blue in the picture)

Open Ended

Give an example of a metal. How do you know it is a metal? What characteristics can you use to explain it is a metal?

______ is a metal because it _________.

Characteristics of Nonmetals

• not shiny

• brittle (breaks apart easily)

• poor conductors of electricity

• mostly gasses at room temperature

• RIGHT SIDE, except Hydrogen (yellow in picture)

Open Ended

Give an example of a nonmetal. How do you know it is a nonmetal? What characteristics can you use to explain it is a nonmetal?

______ is a nonmetal because it _________.

Characteristics of Metalloids

• shiny (luster)

• brittle (breaks apart easily)

• can conduct electricity under certain conditions

• can have characteristics of metals and nonmetals

• on the staircase (in the green)

Open Ended

Give an example of a metalloid. How do you know it is a metalloid? What characteristics can you use to explain it is a metalloid?

______ is a metalloid because it _________.

Groups are vertical columns.

• Groups go UP and DOWN.

•  All elements in a group have the same amount of valence electrons (outer shell)

Periods are horizontal rows.

• Periods go ACROSS.

• All elements in a period have the same number of electron shells.

  
  

Multiple Choice

A group is a vertical column.

• true

• false

Multiple Choice

Elements in the same period have the same number of valence electrons.

• true

• false

Multiple Choice

The element Oxygen (O) has an atomic number of 8. What period is it in?

https://www.ducksters.com/science/periodic_table_lg.jpg

• 16

• 1

• 2

• 15

Multiple Choice

The element Beryllium (Be) has atomic number of 4.

What group is it in?

https://www.ducksters.com/science/periodic_table_lg.jpg

• 1

• 2

• 3

• 4

Chemical Formulas and Subscripts

Elements in a formula (compound) are written with their Symbol and then a small number to the right of the symbol to show how many atoms of that element there are.

Multiple Choice

The subscript for Carbon is

• 3

• 8

Multiple Choice

This is an example of a

• chemical formula.

• coefficient.

Physical Changes

• change in shape or size

• change in state of matter (changes between gas, liquid, solid but remains the same element)

• You can undo these changes.

• Examples: cutting a log into smaller pieces, chocolate melting, crushing a metal can.

  
  

Chemical Changes

• formation of a new substance

• energy change (temperature change)

• gas formation (bubbles)

• precipitate (solid forms)

• color change

• smell change

• Examples: frying an egg, leaves changing color in the fall, wood burning, metal rusting.

  
  

Multiple Choice

My ice cream melts. Is this a physical change or a chemical change?

• physical change

• chemical change

Multiple Choice

I leave my bicycle in the rain. There is rust on my chain. Is this a physical change or chemical change?

• physical change

• chemical change

Multiple Choice

My compost had a banana peel. Now I cannot find it in the compost. Is this a physical or chemical change?

• physical change

• chemical change

Multiple Choice

My birthday cake has many candles. I light them. There is light, heat and melting. Is this a physical or chemical change?

• physical change

• chemical change

Density

Density is the amount of mass in a given volume.

Density

Density is calculated by dividing mass by volume: D = m ÷ V.

Density of liquids is usually measured in grams per milliliter (g/mL).

Density of solids is usually measured in grams per cubic centimeter (g/cm3).

Multiple Choice

The egg floats in salt water and sinks in water from the sink. Why does it float in salt water?

• The salt water is more dense.

• The salt water is less dense.

Multiple Choice

You drop a rock into water.

The rock has a mass of 200 grams.

The water has a volume of 100 L.

What is the density?

• 2 cm3

• .2 cm3

• 20 cm3