Chapter 2, Section 2. Interactions of Atoms Compounds – Atoms of more than one type of element that have been chemically bonded together – Often have.

Chapter 2, Section 2

Interactions of Atoms

Compounds – Atoms of more than one type of element that have been chemically bonded together

– Often have different properties than the elements that formed them

Interactions of Atoms

Chemical Formulas

– Show the ratios and types of atoms in a compound NaCl H20 HCl

Interactions of Atoms

Chemical Properties

– Describe changes that occur when one substance reacts with another substance

Bonding

Chemical Bond– Force that holds atoms together in a compound

– Form when atoms share or exchange electrons in their outermost energy level Outer energy level is

considered stable (and won’t form bonds) when it has 8 electrons

Bonding

Covalent Bonds

– Form when atoms share the electrons in their outermost energy levels

Bonding

Molecule – Group of atoms connected by covalent bonds

Bonding

Ionic Bonds – Form when oppositely charged ions join together to form a neutral compound

Bonding

Metallic Bonds

– Occur in metals– Electrons are free to

move from one positively charged ion to another Results in conductivity

Bonding

Polar Molecules

– Molecules with slight positive and negative charges due to unequal sharing of electrons Example: Water

Bonding

Hydrogen Bonds

– Weak bonds formed between the negative end of one water molecule and the positive end of another water molecule

Mixtures

Mixture – Two or more substances that are not chemically combined

Mixtures

Heterogeneous Mixtures

– Not mixed evenly– Each component

retains its own properties

Mixtures

Homogeneous Mixtures

– Evenly mixed– Properties of the

components are often different from the properties of the mixture

– Often called a solution

Separating Mixtures and Compounds

Mixtures vs. Compounds

– Mixtures can be separated by physical means

– Compounds must be separated by chemical means