Semestre 2 Flashcards
Chemical bond
A force that holds two or more atoms together in a compound, when two atoms share one or more pairs of valence electrons.
Atomic number
The number of protons that the atoms has.
Electron movement
An electron moves into energy levels, depending on the distance they are closer or farther from neutrons.
Energy levels (electron).
2-8-18-32-32-18-8-2
Families
7 groups
18 columns
Valence electrons
The number of electrons that you need to form a chemical bond.
Double covalent bond
When two atoms share two pairs of valence electrons.
Triple covalent bond
When two atoms share three pairs of valence electrons.
Covalent compounds
When two or more atoms share valence electrons to form a stable compound.
Characteristics of the covalent compounds
- Low melting and boring points.
- Usually gas or liquid (can be solid).
- Poor conductors of thermal energy and electricity.
Molecule
A group of atoms that are held together by a covalent bond, to act as an independent unit.
Polar molecule
Same quantity of protons and neutrons attracted by the charges in their poles (ex. water).
Independent unit
Group of atoms with their own chemical and physical characteristics.
Chemical formula
Group of symbols and numbers that represent an element in a compound.
Compound
Chemical combination of different kinds of atoms.
Ion
Atom that is no longer neutral, it has lost or gained a valence electron.
Neutral atoms
When it has the same number of protons and electrons.
Ionic bond
Attraction between positive and negative charged ions in and ionic compound.
Metallic bond
A bond formed when many metal atoms share their pooled valence electron.
Metal characteristics
- Shiny.
- Good conductor of thermal energy.
- Ductile - can be stretched into wire.
- Malleable - can be beaten into thin sheets.
Non-Metal characteristics
- Poor conductors of heat and electricity.
- Non-ductile.
- Do not possess metallic luster.
- Low density.
Covalent bond
- Gas, liquid or solid.
- Low melting and boiling points.
- Poor conductors.
- Dull appearance.
Ionic bond characteristics
- Solid crystals.
- High melting and boiling points.
- Poor conductors.
Metallic bond characteristics
- Usually solid.
- High melting and boiling points.
- Good conductors.
- Shiny surface.
- Can be easily pulled into wires.
Binary compounds
Composed of two elements:
- Metal and non-metal.
- Two non-metals.
Binary ionic compound
Contain cation and anion, metal (loses electrons) + nonmetal (gains electrons) = ions.
Type compounds
- One type of cation. (metal)
2. Two or more cations with different charges. (metal)
Hallogen
A element located in Group VIIA of the periodic table . Halogens are reactive nonmetals having deben valence electrons.
