ChemistryChemistry

Atoms – The basic building

blocks of all the

substances in the

universe. All things

are made up of

atoms.

MATTER is never created or destroyed, it only changes form.

Elements – Are made of one kind of atom; grouped together. The periodic table is 110 different type of elements.

1. Like atoms make up elements2. 110 elements make up all the

known substances on earth!!! (name something)

Atoms contain one or more PROTONS, NEUTRONS, and ELECTRONS

• Protons and neutrons make up the nucleus of an atom.

• Electrons “float” around the nucleus of an atom.

nucleus

Electrons

• The nucleus of the atom is positively charged (+). The negatively (-) charged electrons surround the nucleus to

balance the charge of the atom

to neutral. – The number of protons equals the

number of electrons.

The number in the right corner of each element represents the amount of protons that element has……thus the amount of electrons.

1. Electrons circle around the nucleus in shells or energy levels.

2. As an element looses an electron it looses energy and as an element gains electrons it gains energy.

3. Each circle or shell is limited to how many electrons it can hold.

• Valence electrons – electrons in the outermost energy level of an atom.

• The valence shell can have 1 to 8 electrons in it depending on its place on the periodic table. Elements to the left have 1 and elements to the right have 8.

• Electrons in valance shells that are not full will either gain electrons to become full or give up electrons allowing its outer shell to be lowered to its next lowest level (which is full).

• Ionic bonding – bonding that involves a transfer of electrons. Elements tend to want a full outer shell, thus giving up electrons to other elements or gathering electrons from other elements.

• Example Na+ and Cl-

Mg2+ and O2-

• Ionization energy – is the process of removing electrons and forming ions.

• Ions – a charged atom, positive or negative charge.

• The fewer electrons per shell the less energy needed to pull the electrons away from that element.

• The greater the amount of electrons per shell the higher the ionization energy needed to “pull” the electrons away from that element.

Crystal Lattice – is the placement of ions in an ionic compound that results in a regular,

repeating arrangement.

Because?

like repels like and opposites attract.

Compound – A substance made of two or more elements chemically combined in a specific ratio, or proportion.

Mixture – Two or more substances that are mixed together but not chemically combined.

Solution – A well mixed mixture.

 

 

 

Physical Change – A change that alters the form or appearance of a material but does not make the material into another substance.

 

 

Chemical Change – A change in matter that produces a new substance.

 

Precipitate – A solid that forms from a solution during a chemical reaction.

Molecule – A particle made of two or more atoms that are covalently bonded together.

•The key characteristic of a chemical reaction is the production of new materials that are chemically different from the starting materials.

 

   Chemical reactions occur when chemical bonds break or when new bonds form.

precipitate of cadmium sulfide forms from clear

solutions of sodium sulfide and cadmium nitrate.

Covalent bonds

Covalent bonding – Bonding of atoms in which electrons are shared.

exp. H H

Electron dot diagram – chemists way of expressing the sharing or placement of electrons.

Diatomic elements – Covalent bonding that takes place between atoms of the same element. (hydrogen, bromine, oxygen, iodine, and nitrogen)

Polyatomic ion – A group of covalently bonded atoms that act like a single atom when combining with other atoms. (OH1- hydroxide) pg 24.

Metallic Bonding

Metallic bond – bond formed by atoms of metals, in which the outer electrons of the atoms form a common electron cloud.

•The atoms of metals form metallic bonds

•metals are elements that give up electrons easily.

•Metals are ductile, malleable, and good conductors.•Ductile – The ability to be stretched without breaking.•Malleable – the ability to be flattened or hammered and still hold together.•Conductor – something that has the ability to carry heat or electricity.

•OXIDATION NUMBER

•Oxidation number - is the number of electrons an atom gains, loses, or shares when it forms a chemical bond.

        Na1+ looses one electron thus making atom overall charge positive        Mg2+ looses two electrons thus making atom charge positive        B3+

        N3- gains three electrons making overall charge negative        P3-         O2- gains two electrons making overall charge negative        Cl1-

•The sum of oxidation numbers must equal zero when combining elements into compounds.

•Na 1+ and Cl 1- equal zero NaCl.