Science review

Atom

The basic unit of a chemical element consisting of protons neutrons and electrons.

What are the three subatomic particles that make up an atom?

Protons neutrons and electrons.

Proton

A positively charged subatomic particle located inside the nucleus of an atom.

Where is a proton located and what is its electrical charge?

It is located in the nucleus and has a positive (+1) charge.

Neutron

A subatomic particle with no charge (neutral) located inside the nucleus of an atom.

Where is a neutron located and what is its electrical charge?

It is located in the nucleus and has a neutral (0) charge.

Electron

A negatively charged subatomic particle that orbits the nucleus in the electron cloud.

Where is an electron located and what is its electrical charge?

It is located in the electron cloud surrounding the nucleus and has a negative (-1) charge.

Nucleus

The dense positively charged central core of an atom containing protons and neutrons.

Which subatomic particles make up the mass of the nucleus?

Protons and neutrons.

Electron cloud

The region surrounding an atom's nucleus where electrons are most likely to be found.

Atomic number

The number of protons in the nucleus of an atom which determines the element's identity.

If an atom has an atomic number of 11 which element is it and how many protons does it have?

It is Sodium (Na) and it has exactly 11 protons.

Mass number

The total number of protons and neutrons in an atom's nucleus.

How do you calculate the number of neutrons in an atom?

Subtract the atomic number (protons) from the mass number.

An atom has a mass number of 23 and an atomic number of 11. How many neutrons does it have?

12 neutrons (23 minus 11).

An atom has 6 protons and 8 neutrons. What is its mass number?

14 (6 protons plus 8 neutrons).

Energy level (electron shell)

The specific regions around the nucleus where electrons travel and are arranged.

Valence electrons

The electrons located in the outermost energy level of an atom that participate in chemical bonding.

Why are valence electrons important?

They determine an element's chemical reactivity and how it will bond with other atoms.

Electron configuration

The specific distribution and arrangement of electrons in an atom's energy levels.

What is the maximum number of electrons that can fit in the first energy level?

2 electrons.

What is the maximum number of electrons that can fit in the second energy level?

8 electrons.

Write the basic electron configuration for an atom with 10 electrons (Neon)

2-8

Write the basic electron configuration for an atom with 11 electrons (Sodium)

2-8-1

Octet rule

The tendency of atoms to gain lose or share electrons to obtain a full outer shell of 8 valence electrons.

Why do atoms form chemical bonds according to the octet rule?

To achieve a stable electron configuration with 8 valence electrons like a noble gas.

Chemical bond

The attractive force that holds atoms or ions together to form more stable compounds.

Periodic table

A chart organizing elements by increasing atomic number and showing repeating chemical properties.

Period

A horizontal row on the periodic table.

What does the period number tell you about an atom?

The period number corresponds directly to the total number of electron shells the atom has.

If an element is in Period 3 how many electron shells does it have?

It has exactly 3 electron shells.

Group (family)

A vertical column on the periodic table containing elements with similar chemical properties.

What does the group number tell you about main group elements?

The group number corresponds directly to the number of valence electrons the atom has in its outer shell.

If a main group element is in Group 17 (7A) how many valence electrons does it have?

It has 7 valence electrons.

Metal

An element that is typically shiny malleable ductile and a good conductor of heat and electricity.

Where are metals located on the periodic table?

Metals are located on the left side and center of the periodic table.

Nonmetal

An element that is typically dull brittle and a poor conductor of heat and electricity.

Where are nonmetals located on the upper right side of the periodic table?

Nonmetals are located on the right side of the periodic table (plus Hydrogen on the left).

Metalloid

An element with properties that are intermediate between those of metals and nonmetals.

Where are metalloids located on the periodic table?

Metalloids are located along the staircase border line separating metals from nonmetals.

Alkali metals

The highly reactive elements located in Group 1 of the periodic table (excluding Hydrogen).

How many valence electrons do alkali metals have and what charge do they form?

They have 1 valence electron and form a +1 charge.

Alkaline earth metals

The reactive metallic elements located in Group 2 of the periodic table.

How many valence electrons do alkaline earth metals have and what charge do they form?

They have 2 valence electrons and form a +2 charge.

Transition metals

The elements located in Groups 3 through 12 that often form colored compounds and have variable charges.

What does a Roman numeral next to a transition metal's name indicate?

The Roman numeral shows the specific positive charge of that transition metal ion.

What is the charge of Iron in Iron (III) chloride?

A +3 charge.

Halogens

The highly reactive nonmetal elements located in Group 17 of the periodic table.

How many valence electrons do halogens have and what charge do they form?

They have 7 valence electrons and form a -1 charge.

Noble gases

The highly stable unreactive nonmetal gases located in Group 18 with full outer electron shells.

Why are noble gases unreactive?

They already have a full outer energy level (8 valence electrons) and follow the octet rule.

Lewis dot diagram

A structural representation that uses dots around an element's symbol to show its valence electrons.

What do the dots in a Lewis dot diagram represent?

The valence electrons of the element.

Ionic bond

A chemical bond formed when valence electrons are transferred from a metal to a nonmetal.

How do atoms form an ionic bond?

A metal atom loses electrons to become a positive cation and a nonmetal gains those electrons to become a negative anion.

Give an example of an ionic compound

NaCl (Sodium chloride) or MgO (Magnesium oxide).

Covalent bond

A chemical bond formed when two nonmetals share one or more pairs of valence electrons.

How do atoms form a covalent bond?

Two or more nonmetal atoms share valence electrons so that each atom can satisfy the octet rule.

Give an example of a covalent compound

H2O (Water) or CO2 (Carbon dioxide).

Metallic bond

A bond formed by the attraction between positively charged metal ions and a surrounding sea of mobile electrons.

What allows metals to conduct electricity well?

The free-flowing sea of mobile valence electrons within the metallic bond structure.

Give an example of a metallic compound or structure

Copper wire (Cu) or Iron casing (Fe).

Polar covalent bond

A covalent bond where electrons are shared unequally due to a difference in electronegativity.

What happens to electrons in a polar covalent bond?

The atom with higher electronegativity pulls the shared electrons closer creating partial positive and negative charges.

Nonpolar covalent bond

A covalent bond where electrons are shared equally because the atoms have similar electronegativities.

What is the main difference between polar and nonpolar covalent bonds?

Polar bonds share electrons unequally while nonpolar bonds share electrons completely equally.

Polyatomic ion

A covalently bonded group of atoms that carries a net positive or negative charge and acts as a single unit.

Give an example of a polyatomic ion

Carbonate (CO3^2-) or Sulfate (SO4^2-).

Cation

A positively charged ion formed when an atom loses one or more valence electrons.

What type of elements typically form cations?

Metals form cations by losing outer electrons.

Anion

A negatively charged ion formed when an atom gains one or more valence electrons.

What type of elements typically form anions?

Nonmetals form anions by gaining outer electrons.

Formula

An expression using chemical symbols and subscripts to show the exact ratio of atoms in a compound.

Molecule

A neutral group of atoms joined together tightly by covalent bonds.

Compound

A substance made up of atoms of two or more different elements chemically bonded together.

Electronegativity

A measure of an atom's ability to attract shared electrons toward itself in a chemical bond.

Which group on the periodic table has the highest electronegativity?

Group 17 (The Halogens).

How do you name a Type 1 Ionic Compound?

Name the metal first then name the nonmetal with an -ide ending.

Name the Type 1 Ionic Compound: NaCl

Sodium chloride

Name the Type 1 Ionic Compound: MgBr2

Magnesium bromide

How do you name a Type 2 Ionic Compound with transition metals?

Name the metal first include its charge as a Roman numeral in parentheses then name the nonmetal with an -ide ending.

Name the Type 2 Ionic Compound: FeCl2

Iron (II) chloride

Name the Type 2 Ionic Compound: FeCl3

Iron (III) chloride

How do you name an ionic compound that contains a polyatomic ion?

Name the metal cation or ammonium first then write the exact name of the polyatomic ion without changing its ending.

Name the Polyatomic Ionic Compound: CaCO3

Calcium carbonate

Name the Polyatomic Ionic Compound: Na2SO4

Sodium sulfate

How do you name a binary covalent compound made of two nonmetals?

Use Greek prefixes to show the number of atoms for each element and change the second element's ending to -ide.

What is the special rule for using the prefix "mono-" in covalent naming?

Never use "mono-" on the very first element name only use it on the second element.

Name the covalent compound: CO

Carbon monoxide

Name the covalent compound: CO2

Carbon dioxide

Name the covalent compound: N2O5

Dinitrogen pentoxide