Bonding flashcards

1st=2 2nd&3rd=8 4th=18. A cation is a positevly charged ion that forms when, usually a metal, loses 1 or more electrons (can be multivalent). An anion is formed when, usually a nonmetal, gains one or more electrons (gains "ide" ending).

They form when valence electrons transfer from one cation to an anion. A cation and anion are attracted to one another by charge, forming a neutral compound joined by an ionic bond.

• It is a specific volume of space in which an electron of certain energy is likely to be found. It can be unoccupied, contain one e- which is an unpaired/bonding e- or contain two e-'s which is a lone pair/nonbonding e-. 
• The first enrgy lvl contains 1 orbital (H&He), energy lvls above the first contain 4 orbitals each. Electrons spread out to occupy empty orbitals before forming pairs.

Groups determine the number of valence e-'s and atom has. While period determine the numbers of energy levels an atom had

Electronegativity is the relative ability of an atom to attract bonding e-'s. It increases with decreased number of energy levels as the farther away from the nucleus e-'s are, the weaker their attraction to the nucleus. It also increases with atomic number within a period, because the greater number of protons in the nucleus, the greater the attraction for electrons. Metals tend to have low electronegativities while nonmetals tend to have high ones (flourine has highest) which is why ionic compounds are usually metal nonmetal.

The octet (duet rule for H+ cause 1 enrgy lvl) rule states that chemical ractions incolce the sharing or transfer of valence e-'s so that each atom has a complete valence shell, or stable octet. Atoms with full valence shells are more stable, which is why noble gases are so stable. Main group atoms usually obey the octet rule (carbon,nitrogen, oxygen and flourine).

It is the simultaneous attraction of oppositely charged ions. They form when the electronegativity difference between atoms is greater than 1.7. This results in the complete transfer of one or more electrons from the atom with the lower electroneg. to the atom with the higher electroneg. Since metals have lower electronegativities and nonmetals have higher ones ionic compounds are composed of a metal and nonmetal.

Lewis symbols or electron dot diagrams are structural representations of the location of valence electrons in an atom. First the element symbol is written in the middle (represents nucleus and any filled enrgy lvls), Then electrons are represented with dots that surround the element symbol (each of the 4 sides represent an orbital, first fill up w bonding e-'s then begin making lone pairs). Last, square brackets are placed around the ions and charge is written on the outside.

Ions arrange themselves in a crystal lattice in order to achieve maximum total attraction between cations and anions. It is non-directional because an ion has the same attraction from all directrions for an ion of opposite charge.

Due to ionic bonding and crystalline structure ionic compounds have these characteristics:

• 1. They are hard because non directional ionic bonds are strong and difficult to break
• 2. They are brittle because ions cannot be rearranged without breaking the crystal lattice
• 3. They have a high melting point because ionic bonds require large amounts of enrgy to break and ions are bonded in all directions
• 4. Most are soluble in water due to attraction between ions and polar water molecules (But some are not, reference solubility chart)
• 5. Liquid/Molten states and solutions of ionic compounds are electrolytic (conduct electricity) due to the presence of moving ions.
• 6. They are relatively stable and unreactive at SATP (standard ambient temp. and pressure) because they have full valence shells.

A molecule is an independent unit made up of fixed numbers of nonmetallic atoms help together by covalent bonds. Molecular elements do not exist naturally as single atoms, they consist of two or more nonmetallic atoms of the same element (covalent bonds). Diatomic elements are composed of two atoms of the same element joined by a covalent bond. The diatomic ones are H₂, O₂, F₂, Br₂, I₂, N₂, Cl₂. The polyatomic ones are P₄ and S₈.

Name	Chemical Formula
water	H₂O(l)
hydrogen peroxide	H₂O₂(l)
ammonia	NH₃(g)
glucose	C₆H₁₂O₆(s)
sucrose	C₁₂H₂₂O₁₁(s)
methane	CH₄(g)
ethane	C₂H₆(g)
propane	C₃H₈(g)
methanol	CH₃OH(l)
ethanol	C₂H₅OH(l)

Covalent bond is the simultaneous attraction of two nuclei for a shared pair of bonding electrons, forming a strong directional intramolecular force and giving each atom a complete valence shell. It occurs when the electronegativities of both atoms (usually nonmetals) are relatively high and the electronegativity difference between atoms is 1.7 or less. Single covalent bonds involve one pair of shared e-'s, Double covalent bonds is a multiple bond that consists of 2 e-'s, triple covalent bonds consist of 3 e-'s. Bonding capacity is the max number of single covalent bonds an atom can form. It is determined by the number of bonding electrons. Atom with bonding capacity of 3 can form 3 single bonds, 1 single and 1 double bond or 1 triple bond.

• Empirical formula shows the simplest whole number ratio of atoms in the compounds (can be technically incorrect).
• Molecular formula shows the actual number of atoms that are covalently bonded to make up each molecule (usually arranged to show atom configuration). 
• Lewis formula shows the electron sharing and formations of stable valence octets of electrons in molecules and ions (always draw this first).
• Structural formula shows which atoms are bonded and the type of covalent bond is represented by the number of lines drawn between atomic symbols.

It is the study of the 3D spatial configuration of molecules. Valence-shell-electron-pair-repulsion (VSEPR) theory states that pairs of electrons in the valence shell of an atom stay as far apart as possible because of the repulsion of their negative charges. The molecular shape is determined by the positions of the electron pairs when they are a maximum distance apart and whether they are bond pairs or lone pairs. The order of repulsion is LP - LP > LP - BP > BP - BP.

• A nonpolar bond occurs when there is a symmetrical charge distribution among atoms. These atoms have an electronegativity difference of 0.4 or less.
• A polar covalent bond is when electrons spend more time closer to one atomic nucleus than another (asymmetrical), resulting in a partial positive and partial negative end. The overall charge of the molecule is still zero, they need an electronegativity difference greater than 0.4 but less than or equal to 1.7. The greater the electronegativity difference the more polar the bond.

• Bond polarity is shown with a vector arrow, pointing from the partial positive to the partial negative side of the bond (from lower to higher electroneg.). The vector arrow represents the bond dipole.
• Dipoles are when a bond has two poles and one is negative and the other is positive.
• A nonpolar molecule may have polar bonds, but the bond dipoles balance each other to produce a molecular dipole (vector sum) of zero (symmetrical)

Intermolecular forces are the forced of attraction and repulsion between molecules. The three types are the dipole dipole force which is the attraction between permanent dipoles in adjacent polar molecules (more polar=stronger dipoles force). Next is LDF which results from the momentary or induced dipoles due to electron movement, it occurs in all substances and they increase as the total number of electrons increase. The last type is hydrogen bonds which occur when a hydrogen bonds to a highly electronegative atom with a lone pair (FON). The highly electronegative atom pulls electrons away from the hydrogen resulting in the attraction between the lone pair and the unshielded hydrogen proton on an adjacent. Intermolecular forces are weaker than ionic and covalent bonds (requires less energy to boil water rather than to decompose it). Intramolecular forces are between molecules, they are the forces that keep molecules together (ionic and covalent bonds).

They are molecules that have the same number of electrons, and therefore, the same London force. Enthalpy of fusion is the amount of energy required to change one mole of a substance from solid to liquid. Enthalpy of vaporization is the amount of energy required to change on mole of a substance from liquid to gas. To predict solubility solute-solvent attractive forces must be able to overcome the solute-solute interactions and the solvent solvent attractions. Polar is soluble in polar and non polar is soluble in non polar and hydrogen bonded molecules are soluble in hydrogen bonded solvents.