chapter 2, section 2. interactions of atoms compounds – atoms of more than one type of element...
TRANSCRIPT
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