chapter 5 Flashcards
compounds vs. mixtures.
distinguished by chemical bonds. Compounds are held together by chemical bonds. Mixtures have no chemical bonds.
Chemical Bond
the attractive force that holds atoms or ions together
- Ionic Bond
- Covalent Bond
- Metallic Bond
- Polyatomic Ion
Chemical structure
the arrangement of atoms in a substance
crystalline structure is any structure of ions, molecules, or atoms that are held together in an ordered, three-dimensional arrangement.
amorphous structure is irregular and lacks the repeating pattern of a crystal lattice.
Bond Length
the average distance between the nuclei of two bonded atoms
Bond Angle
the angle formed by two bonds to the same atom, so you at leas have to have 3 atoms in a molecule, since a two atom molecule will always have the same bond angle of 180 deg.
Crystalline compound
Crystalline compound are strong solids with high melting and boiling points. A crystalline structure is any structure of ions, molecules, or atoms that are held together in an ordered, three-dimensional arrangement. Can be thought of as the highest level of order that can exist in a material. ex: SiO2, NaCl, MgF2.
Some compounds are made of networks of bonded ions.
Like salt.
Some compounds are made of molecules.
Molecule compounds can be liquids gases, and solids. depending on the strength of the attraction between their molecules for each other, like in H2O to H2O (moderate attraction), Sugar (~strong attraction) & gas H2S (weak attraction).
Substances made of molecules have lower ________
melting points.
whether a molecular substance is a solid, a liquid, or a gas at room temperature depends on the _______
attractions between its molecules, as per the Kinetic Theory of Matter.
Attraction between water molecules is due to_________
hydrogen bonds – a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.
Bonded Atoms usually have a stable_____.
electron configuration.
Atoms bond when their valence electrons interact.
Ionic Bond
a bond formed by the attraction between oppositely charged ions. Formed by transfer of electrons.
Atoms strive to be closer to the noble gas electron shell configuration…
via Transfer of Electrons. NaCl: Na wants to give up its electron to have a stable shell. Cl wants to take an electron, i.e. Na — e— __> Cl resulting in
Na+ + Cl– —> NaCl.
Metallic Bonds
a bond formed by the attractions between positively charged metal ions and the electrons around them. Electrons move freely between metal atoms.
Covalent Bond
formed when atoms share one or more pairs of electrons.
covalent compounds can be solids, liquids or gases.
Most covalent compounds have low melting points, below 300C.
Covalent Bond vs Ionic Bond
Covalent:
- Atoms share a pair of electors via a covalent bond.
- Atoms don’t transfer electrons because each needs to gain an electron.
Ionic:
- Electrons are fully transferred in ionically bonded compounds.
Atoms may share more than one pair of electrons.
- Single covalent bond: H2
- Double covalent bond: O2;
- Triple Covalent Bond: N2
Polar Covalent Bond:
When atoms don’t share electrons equally. Electrons spend more time closer to one atom than the other.
Polyatomic Ions:
A polyatomic ion, also known as a molecular ion, is a charged chemical species (ion) composed of two or more atoms covalently bonded or of a metal complex that can be considered to be acting as a single unit
A polyatomic ion, also known as a molecular ion are made of two or more atoms.
So it could be two or more pure substances; or two or more compounds. ex. (NH4)2SO4, or NH4NO3.
CATION
cation (+)
Naming ANIONS: change the suffice to IDE:
Florine —> Floride Chlorine —> Chloride Oxygen ==> oxide Sulfur —> sulfide
Metals mostly form Positive ions, CATIONS. There typically have the charge 2/3+
Copper —> copper (I) ion, or copper (II) ion. Iron —> iron (ii) or Iron (iii) ion. Nickel —> nickel (II) ion.
Naming ionic compounds. (ionic formulas)
Whichever element is further to the right in the periodic table is named second and end with “ide”: lithium oxide: Li2O; titanium(III) nitride: TiN; cobalt(III)hydroxide: Co(OH)3 .
Hydroxide ion:
HO—
Naming Covalent Compounds:
N2O4: Dinitrogen tetroxide.
prefixes I don’t know:
- nona— 9;
- hepta — 7;
- Deca — 10;
Empirical formula: (Simplest formula )
composition of a compound in terms of the relative numbers and kinds of atoms in the simplest ratio.
Molecular formula
formula that shows the actual number of atoms in a molecule/compound.
Carbohydrate
Any organic compounds that is made of carbon, hydrogen, and oxygen, and that provides nutrients to the cells of living things.
Amino Acid
any one of 20 different organic molecules that contain a hydroxyl (—OH) and an amino group and that combine to form proteins.
Hydroxyl
−OH
Hydroxyde
A hydroxyl group bonded covalently to the carbon of a carbonyl group (C=O) produces a carboxyl group (C(O)OH) that is the defining group of a carboxylic acid. When the −OH group participates in an ionic bond, the [OH−] anion is called the hydroxide ion.
ANION
anion (−)
