Unit 1 States of Matter - PDF

Unit 1 States of matter Atoms The periodic table Ms. Vimashi Gunaratne MSc. Medical Microbiology (Peradeniya) BSc. (Hons) Medical Laboratory Sciences (KDU)  States of Matter Matter is defined as anything that occupies space and has a mass It is made up of particl...

Unit 1 States of matter Atoms The periodic table Ms. Vimashi Gunaratne MSc. Medical Microbiology (Peradeniya) BSc. (Hons) Medical Laboratory Sciences (KDU)  States of Matter Matter is defined as anything that occupies space and has a mass It is made up of particles  Classification of Matter The different types of matter can be distinguished through two components: composition and properties. Classification of matter by composition Can be separated by Constant physical changes composition Eg ; evaporation Metals Non- Metals Matter Pure substance A pure substance is a material that has a uniform and definite composition. It consists of only one type of substance, which can be either an element (like gold or oxygen) or a compound (like water or sodium chloride). Pure substances have consistent properties throughout, such as melting point, boiling point, and density, and they cannot be separated into other substances by physical means  Compounds A compound is a substance formed when two or more different elements. chemically combine in a fixed ratio. Compounds can be broken down into their constituent elements through chemical reactions Compound: contains 2 or more elements combined in a fixed ratio. Millions of compounds on Earth Elements An element is a pure substance consisting of only one type of atom have the same numbers of protons in their nuclei Each element cannot be broken down into simpler substances by chemical changes. Each element retains its basic physical properties, regardless of the number of atoms in a sample Elements: Natural elements & synthetic elements An element contains one kind of atoms only Fe is made of Fe atoms Ne gas is made of Ne atoms Mixtures A mixture is a combination of two or more substances that retain their individual properties and can be separated by physical means. The components in a mixture can be elements, compounds, or both, and they do not combine chemically. Mixtures can be homogeneous, where the components are evenly distributed (like saltwater), or heterogeneous, where the components are distinct and easily identifiable (like a salad).  Physical properties chemical properties Mixture Molecule 2 or more components Contains two or more atoms physically bonded Air- a mixture of gases, water Elements but molecules O3 O2 vapour, dust particles N2 River water- a mixture of Molecular compounds CO2 NH3 minerals, gases, water H2O Shampoo-several chemicals & water Salt solution Sugar solution Fruit salad  Classification of Matter The different types of matter can be distinguished through two components: composition and properties. Classification of matter by Properties Classification of matter by Properties The characteristics that enable us to distinguish one from another substance are called properties Physical properties can be observed or measured without changing the chemical composition of matter A physical change takes place without any changes in molecular composition. The same element or compound is present before and after the change. Based on the physical properties, there are three states of matter : solid, liquid, gas chemical properties of matter describes its "potential" to undergo some chemical change or reaction by virtue of its composition A CHEMICAL CHANGE alters the composition of the original matter. Different elements or compounds are present at the end of the chemical change. The atoms in compounds are rearranged to make new and different compounds Three States of Matter There are three states (physical states) of matter Solid Liquid Gas Properties of Matter Property Solid Liquid Gas Shape Definite shape No definite shape. No definite shape. Take the shape of Take the shape of the container the container Volume Fixed volume Fixed volume Spreads throughout the entire volume Compressibility Cannot be Hard to compress Can be compressed compressed often Density Often High Often High Low 1.‘A solid has a definite shape unlike liquid and gas’. The particles of a solid are organized in a regular pattern with strong bonding so a solid has a definite shape. But particles of a liquid or gas are not orderly organized. 2.‘Solids and liquids have a definite volume, but gases do not have a definite volume’. The gas particles move in a random manner occupying the entire volume of the container unlike solid or liquid particles having a fixed volume. 3.‘Solid and liquid matter cannot be compressed easily, gaseous matter can be compressed easily’. Gas particles have wider spaces between them so by Kinetic Particle Theory The kinetic particle theory states that matter is made up of tiny particles (atoms or molecules) that are always in motion. The energy and speed of these particles determine the state of the matter: Solids: Particles vibrate in fixed positions. Liquids: Particles are close together but can move past each other. Gases: Particles are far apart and move freely. Temperature is a measure of the average kinetic energy of these particles, and the forces between them influence their behavior. This theory helps explain phenomena like changes of state and gas behavior. Solid Tightly packed particles in an orderly manner (fixed patter called lattice). Particles strongly bonded. They do not move relative to one another, but can vibrate i fixed positions. Liquid Particles are not orderly arranged. The binding forces are not as strong as in a solid. The particles slide past each other. Space among particles is less, but higher than that of a solid. Gas Particles are far apart, show free & random movement. Weak binding forces among the particles. IDENTIFY A PURE substance! Check melting & boiling points, density Heating curve for water Sublimation: solid turns to its gas without passing thro a liquid state Deposition…opposite process Warm iodine crystals-produces a gas Formation of iodine crystals back on a cold surface Sublimation of dry ice or frozen CO2 at room temperature Evaporation of naphthalene or moth balls (vapour kills moths) Atoms: An atom can be described as the smallest particles of matter, that we cannot break down further by chemical means. The atom has the properties of the element. Diameter of a H atom - 10-10 m so its mass is small. It weighs only 1.67×10-27 kg Atomic structure The development of the atomic model Billiard ball (Dalton) Plum pudding (Thomson) Nuclear (Rutherford) Orbital (Bohr) Refined orbital model based on quantum mechanics (Planck, Einstein, Born,…) About 400 BC: Greek philosopher Democritus suggested that all substances consisted of tiny indivisible particles called atoms. 1808 John Dalton’s atomic theory: Billiard ball model proposed that matter is composed of small particles (atoms) which are solid and indestructible – much like a billiard ball.  Nuclear model Atoms are small, solid, indestructible particles Orbital model Plum pudding Chadwick-Bohr model model The modern theory of quantum mechanics has been developed from the work of Rutherford & Bohr. Physicists have discovered around 50 different elementary particles, within atoms…may be even more to discover!! The 3 basic particles may be further subdivided into over 50 other unstable particles, including quarks, leptons, antiparticles, gluons, photons. Modern atomic model Sub-atomic particles make up the atom An atom consists of a nucleus & a cloud of electrons. Nucleus is very tiny compared to the rest of the atom & heavy. The sub atomic particles are very light so their mass is measured in atomic mass units. Electron Distribution Periodic table Names & symbols of elements Families or groups with similar properties The rows are periods, columns are groups The zig-zag line separates metals from non metals The modern periodic table was arranged in the increasing order of atomic or proton number Period number-Gives the number of shells in an atom Group number-Gives the number of outer shell electrons in an atom Isotopes Most elements have isotopes are the variations of the same element have the same proton number but have different nucleon numbers Radioactive isotopes (radioisotopes):Occur naturally, an unstable isotope emits radiation & changes into another kind of atom, C-13 is radioactive. & eventually decay For an atom; proton no. = electron no. = ………… p charge + e charge=……………. so an atom is neutral, has no overall charge. Mass or nucleon no. ……………… Atomic or proton no. ……………… electronic configuration of Na atom: