Periodic Trends, Ionic & Covalent Compounds

Flashcards reviewing key vocabulary and concepts from Chapter 2: Periodic Trends and Chapter 3: Ionic Compounds and 4: Covalent Compounds.

Element

A pure substance that cannot be broken down into simpler substances by a chemical reaction.

Element Symbol

A one- or two-letter shorthand representation of an element's name.

Compound

A pure substance formed by chemically combining two or more elements together.

Chemical Formula

Uses element symbols to show the identity of the elements forming a compound and subscripts to show the ratio of atoms.

Atoms

Basic building blocks of matter.

Proton

A subatomic particle with a positive (+) charge.

Electron

A subatomic particle with a negative (-) charge.

Neutron

A subatomic particle with no charge.

Nucleus

Dense core of an atom containing protons and neutrons.

Electron Cloud

Composed of electrons that move rapidly in the almost-empty space surrounding the nucleus.

Atomic Mass Unit (amu)

A standard mass unit used by chemists, defines the mass of atoms relative to a standard mass.

Atomic Number (Z)

The number of protons in the nucleus of an atom, symbolized by Z.

Mass Number (A)

The sum of the number of protons and neutrons, symbolized by A.

Isotopes

Atoms of the same element having a different number of neutrons.

Atomic Weight (or Atomic Mass)

The weighted average of the mass of the naturally occurring isotopes of a particular element.

Periodic Table

Elements with similar characteristics arranged together in a schematic way.

Period

A row in the periodic table.

Group

A column in the periodic table.

Metals

Shiny substances that conduct heat and electricity.

Nonmetals

Poor conductors of heat and electricity.

Metalloids

Elements with properties intermediate between metals and nonmetals.

Alkali Metals (Group 1A)

Elements that comprise a particular group that have similar chemical properties.

Alkaline Earth Elements (Group 2A)

Elements that comprise a particular group that have similar chemical properties.

Halogens (Group 7A)

Elements that comprise a particular group that have similar chemical properties.

Noble Gasses (Group 8A)

Elements that comprise a particular group that have similar chemical properties.

Principal Energy Levels (Shells)

The regions to which electrons are confined, giving it a particular energy.

Subshells

Shells, identified by the letters s, p, d, and f.

Orbital

A region of space where the probability of finding an electron is high.

Ground State

The lowest-energy arrangement of electrons.

Valence Electrons

The most loosely held electrons, electrons in the outermost shell.

Atomic Radius

The distance from the nucleus to the outer edge of the valence shell.

Ionization Energy

The energy needed to remove an electron from a neutral atom.

Cations

Positively charged ions. A cation has fewer electrons than protons.

Anions

Negatively charged ions. An anion has more electrons than protons.

Electrostatic Attraction

The electrical attraction between oppositely charged ions.

Electron configuration rule

Elements gain, lose, or share electrons to attain the electronic configuration of the noble gas closest to them in the periodic table.

Main group metal cations

Metals in groups 1A, 2A, and 3A tend to form cations with charges equal to the group number.

Main group nonmetal anions

For nonmetals in groups 5A, 6A, and 7A, the anion charge = 8 − (the group number).

Octet Rule

A main group element is especially stable when it possesses an octet of electrons in its outer shell.

Metals

A cation is derived from this element.

Nonmetals

An anion is derived from this element.

Chemical Nomenclature

A chemical nomenclature system used to assign an unambiguous name to each compound.

Polyatomic Ion

A cation or anion that contains more than one atom.

Electronegativity

A measure of an atom’s attraction for electrons in a bond.

Covalent Bond

A two-electron bond in which the bonding atoms share valence electrons.

Molecule

A group of atoms held together by covalent bonds.

Two

A diatomic molecule contains this amount of atoms.

Nonbonded Electron Pairs (Lone Pairs)

In a Lewis structure, these unshared electron pairs are on the atoms.

Number and Identity of Atoms

A molecular formula shows this on the covalent compound.

Lewis Structure

Shows the connectivity between the atoms in a molecule, as well as where all the bonding and nonbonding valence electrons reside.

Double Bond

Four electrons in two two-electron bonds.

Triple Bond

Six electrons in three two-electron bonds.

Resonance Structures

Two or more Lewis structures having the same arrangement of atoms but a different arrangement of electrons.

Across Periodic Table (left to right)

Electronegativity increases in this direction.

Down Periodic Table from top to bottom

Electronegativity decreases in this direction.

Nonpolar Bond

Atoms sharing electrons with equal force.

Polar Covalent Bond

Bond polarity with unequal sharing of electrons.

Dipole

A partial separation of charge.

VSEPR Theory

This principle means that the electrons in valence shell repel each other.

Linear

Two groups around an atom.

Trigonal Planar

Three groups around an atom has 120 degree bond angles.

Tetrahedral

Any atom surrounded by four groups has 109.5 bond degree angles.

Linear Geometry

Has an atom surrounded by only two groups, such as CO2 and HCN.

Trigonal Planar Geometry

Has an atom surrounded by only three groups, such as BF3 and H2C=O.

Tetrahedral Geometry

Has an atom surrounded by four groups, such as CH4, NH3, and H2O.

Types of Chemical Bonds

Ionic, covalent.

What kind of bonds do nonmetals form with each other?

Covalent Bonds.

What happens between a metal and nonmetal

Electrons are transferred.

What could a decrease in the ozone layer trigger?

An increase in cancer rates, like skin cancer.

what is nomenclature

A general name for naming compounds.

net dipole

The sum of all the bond dipoles in a molecule.

What are metals bonding to nonmetals?

Ionic compounds.

What is the general bonding rule?

Elements gain, lose, or share electrons to obtain the electronic configuration of the noble gas closest to them in the periodic table.

What identifies the element?

The number of protons.

How do metal atoms become cations?

By removing one or more electrons.

How do nonmetal atoms become anions?

By gaining one or more electrons.

What is the goal of 3A, 5A, 6A, and 7A elements in bonding?

They must add electrons to achieve an outer energy level containing an octet of electrons.

How are ionic compounds named?

Name of metal cation followed by name of nonmetal anion.

What holds ionic compounds together?

The electrostatic forces between the resulting oppisitely charged ions.

What characterizes ionic bonding?

Transfer of one or more electrons takes place between atoms.

What is electronegativity?

The ability of an element to attract electrons to itself in a chemical bond.

What are the trends of electronegativity in the periodic table?

Increases from left to right across a row and decreases from top to bottom down a group.

What are polar covalent bonds?

One in which electrons are shared unequally.

What does VSEPR theory predict?

The shape of a molecule.

What is the number of electron pairs in a covalent bond?

Two.

What characterizes covalent bonding?

The sharing of electrons between atoms.

What types of atoms form covalent bonds with each other?

Nonmetals.

What is revealed by a molecular formulat for a compound?

The number of atoms and which kinds of atoms found in a given compound.

What bonds exist in Lewis structures for covalent compounds?

Drawn single, double, and triple bonds to indicate shared pairs of electrons between all the bonded atoms in the molecule.

What is the main goal of covalent bonding?

Atoms gain, lose, or share electrons until they are surrounded by valence electrons with the same electronic configuration as the nearest noble gas.

What does the line in a Lewis dot stricture show?

Show a two-electron covalent bond that represents both atoms sharing valence electrons.

How many valence electrons does an atom from the period 2 elements contain?

Two (hydrogen) or eight (the elements carbon through fluorine).

What results when atoms of differing electronegativities bond with each other?

The unequal sharing of electrons.

How is the polarity of a bond indicated?

With the head of the arrow pointing to the more electronegative elements.

What does the tetrahedreal geometry about carbon arise on?

From the electron configuration of carbon.

What are the geometries possible for a carbon atom.

Tetrahedral, trigonal planar, or linear.

What are resonance structures?

Lewis structures where it is possible to draw two or more electronically equivalent covalent molecules with differing locations of single and double or triple bonds.

How are models useful?

They are useful for gaining insights into how molecules and ions behave.

What is it about crude oil as a covalent material?

It exists as either a pure compound or a complex mixture.

What gas is a toxic product of incomplete combustion that binds strongly to the transport protein hemoglobin?

Carbon monoxide (CO).