Chapter 3 Classification of Matter Objectives: Define and give examples of 3 states of matter (3.1 & 3.2) Distinguish between substances and mixtures (3.3 & 3.12) Understand what elements are ( ) Distinguish between metals, nonmetals and metalloids (3.8) Define compounds and diatomic molecules (3.9 & 3.10) Be able to write chemical formulas (3.11)

What is Matter? Anything that has mass and occupies space Composed of atoms Exists in three states on earth Solid Liquid Gas Exists in fourth state in space Plasma

Solids Definite shape and volume Particles tightly packed Crystalline – salt, sugar, quartz Amorphous solids – no regular, geometric pattern

Liquids Definite volume Not a definite shape (Takes shape of container) Particles have more energy Particles can move freely

Gases Indefinite volume No definite shape Particles have high energy level Particles move independently of one another

Substances and Mixtures Pure Substance: a particular kind of matter with a definite, fixed composition Elements (copper, gold, oxygen) Compounds (sugar, salt, water) Mixture: a blend of two or more pure substances Not chemically combined

Matter Pure substances (homogeneous composition) Mixtures of two or more substances ElementsCompounds Solutions (homogeneous composition – one phase) Heterogeneous mixtures (two or more phases) Figure 3.2 (page 48)

Types of Mixtures Heterogeneous mixtures Visibly different parts Chocolate chip cookies; granite Two or more phases (usually) Homogeneous mixtures Different parts not visible (uniform throughout) One phase Seawater; air

Separating Mixtures Do NOT cause chemical changes Heterogeneous Mixtures Filtration

Separating Mixtures Homogeneous Mixtures Distillation

Separating Mixtures Homogeneous Mixtures Chromatography

Separating Mixtures Homogeneous Mixtures Crystallization

Pure Substances Elements A substance that cannot be separated into simpler substances Compound Two or more elements combined through a chemical reaction Different properties than elements which compose it

Elements ~111 presently known elements Building blocks of all substances At room temperature: 2 liquid 11 gases All others solid Figure 3.3 – distribution of elements in galaxies, earth’s crust, seawater and air, and human bodies

Elements Names of the elements Greek Latin German Properties of elements Scientist who discovered it Location where discovered

Elements Arranged in the Periodic Table (inside front cover) Symbols One or two letters Usually part of name (Table 3.3, pg 52) Some symbols are Latin/Greek name (Table 3.4, pg 52)

Elements Classificiation Metal Nonmetal Metalloid See Table 3.5 (page 54)

Elements Metals: Usually solid at room temperature Good conductors of heat and electricity High luster Ductile Malleable High melting point; high density Usually don’t combine with each other Readily combine with nonmetals

Nonmetals: Solids (C, P, S, Se, I); Liquid (Br); Gases (all others) Poor conductors of heat and electricity; no luster Low melting point; low density Will combine with each other (CO 2 ) Will combine with metals or metalloids Some found uncombined in nature (noble gases)

Elements Metalloids Have properties of both metals and nonmetals Some used for semiconductors in electronics

Compounds Two or more elements chemically combined New properties Definite proportions Can be chemically separated Molecular or Ionic

Compounds Molecular Held together with covalent bonds Molecule: smallest uncharged individual unit of a compound Water is an example

Compounds Ionic Ion: positively or negatively charged atom or group of atoms Cation – positive Anion – negative Held together by ionic bond – attraction between positive and negative charges

Compounds Diatomic Molecules Always only 2 atoms 7 naturally occurring Hydrogen, oxygen, nitrogen, flourine, chlorine, bromine, iodine H 2, O 2, N 2, F 2, Cl 2, Br 2, I 2,

Chemical Formulas Abbreviations for compounds Symbols and ratios of atoms Sodium Chloride (NaCl) 1 atom of sodium for every 1 atom of chlorine Number 1 not usually written

Subscript indicates # of atoms present H 2 O has 2 Hydrogen atoms and 1 Oxygen atom H 2 SO 4 has NaOH has C 6 H 12 O 6 has 2 hydrogen atoms, 1 sulfur atom, 4 oxygen atoms 1 sodium atom, 1 oxygen atom, 1 hydrogen atom 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms

Chemical Formulas Parentheses are used to show when a compound contains more than one group of atoms that occurs as a unit Calcium Nitrate Ca(NO 3 ) 2 has 1 calcium, 2 nitrogen, and 6 oxygen atoms Ba 3 (PO 4 ) 2 has 3 barium, 2 phosphorus, and 8 oxygen atoms

Chemical Formulas Show only number and kind of atom Do not show arrangement of the atoms or how chemically bonded