science grade 8 (unit 1) - drcilearn.com

Science 8

DEL ROSARIO CHRISTIAN INSTITUTE

TABLE OF CONTENTS:

UNIT 1 : Matter

Lesson 1: The Nature of Matter Lesson 2: Changes in Matter Lesson 3: Elements, Compounds, Mixtures Lesson 4: Atomic ParticlesLesson 5: Periodic Table of Elements

UNIT 2 :l iv ing things and their environment

Lesson 6: Structures and Functions of the Digestive System Lesson 7: Heredity: Inheritance and Variation of TraitsLesson 8: BiodiversityLesson 9: Transformation of Energy Lesson 10: Biogeochemical Cycles

UNIT 3 : force, motion and energy

Lesson 11: Newton's Law of MotionLesson 12: Forms of EnergyLesson 13: PowerLesson 14: The Propagation and Speed of SoundLesson 15: Heat and TemperatureLesson 16: Electricity and Magnetism

UNIT 4:Earth and space

Lesson 17: Understanding EarthquakesLesson 18: Understanding StormsLesson 19: The Development of a TyphoonLesson 20: Philippine Tropical CyclonesLesson 21: CometsLesson 22: AsteroidsLesson 23: Meteoroids, Meteors, and Meteorites

UNIT 1UNIT 1LESSON 1: THE NATURE OF MATTER

The Particulate Nature of Matter

All matter is particulate in nature. This basically means that between separate bits of matter there arespaces which contain no matter. In science it is called the "atomic nature of matter".

It is generally agreed that the Greek philosopher Leucippus and his student Democritus in the Schoolof the Atomos, were the first to propose this idea, about 440 B.C.

Democritus described atom as indivisible, indestructible and uncuttable.

Matter is made up of discrete particles, called atoms or their combinations, called molecules orcompounds.

Classification of Matter by Composition

Del Rosario Christian Institute Inc.

Properties of Solids, Liquids, and Gases

There are four states of matter: solid, liquid, gas, and plasma. Plasma is considered the fourth state ofmatter and exists only at a relatively high temperature like the particles in the surface of the sun will not behighlighted.

The Particle Model illustrates the differences and commonalities of solids, liquids, and gases in termsof volume, shape, compressibility, and density or molecular arrangement among others.

ACTIVITY 1: Make a representation of the atoms in each state of matter.

SOLID LIQUID GAS

LESSON 2: CHANGES IN MATTER Phase change is defined as the transition of one phase of matter to another. Some of theseprocesses are classified as physical change. Solid can change into liquid through liquefaction or melting. Aliquid can change into a solid through solidification or freezing. Liquid can change into gas through theprocess of vaporization and gas can change into liquid through the process of condensation. Throughsublimation, solid can transform into gas and through deposition, gas can transform into solid.

Phase Change and Processes


matter changing FROM A SOLID TO A LIQUID.Energy is addedWhen more heat (energy) is added to matter the particles move faster till the bonds break.Decrease density except ice to water.

Matter changing FROM A LIQUID TO A GAS.ENERGY IS ADDED TO SURFACE OF LIQUIDTHE PARTICLES AT THE SURFACE MOVE FASTER breaking bonds.Decreases density.

There are three possible changes that can happen to a material - physical, chemical, and nuclearchange.

Physical change is a phase change. It is classified into two types: extrinsic physical change, which isdependent on the amount of matter and intrinsic physical change, which is independent of the amount ofmatter.

Chemical change results in the formation of new substances where the original properties orcharacteristics of the reactants are totally altered and the resulting products are entirely different from theoriginal raw materials.

Nuclear change involves nuclear reaction, by fusion or fission, of an element's atomic nuclei.

Types of Phase Changes

1.Melting

2. Evaporation

matter changing FROM A LIQUID TO A GAS ALL THROUGHOUT THE LIQUIDENERGY IS ADDED TO ALL OF LIQUIDPARTICLES MOVE FASTER ALL THROUGH THE LIQUIDSOME PARTICLES MOVE FAST ENOUGH TO CHANGE TO GAS WHILE THEY ARE IN THE MIDDLE OF THELIQUIDDENSITY DESCREASES

Remember that vaporization is a general word for any substance changing to a gas.Boiling, evaporation, and sublimation are ALL examples of vaporization.

Matter CHANGING FROM A GAS TO A LIQUIDENERGY IS REMOVE

changing from a liquid to a solidenergy is removed

Solidification is a general word for any substance changing to a solid.Freezing and deposition are examples of SOLIDIFICATION.

matter changes straight from a solid to a gas.Heat added rapidlyMolecules speed up and spread out rapidlydecrease density

Deposition- when matter changes from a gas directly to a solid.Heat is taken away rapidlyDensity increasesMolecules slow down and get closer together.

3. Boiling

Examples: pan of liquid on the stove

Vaporization

4. Condensation

Examples: dew in the lawn, water running down mirror, ring on table under glass.

5. Freezing

Examples: water to ice, wax or chocolate hardening

Solidification

6. Sublimation

Examples: dry ice, shrinking ice in a freezer, air freshener.

7. Deposition

Examples: Snowflakes, frost on a wind shield


ACTIVITY 1: Put all the items in the correct box according to their state of matter.


LESSON 3: ELEMENTS, COMPOUNDS, MIXTURES

Atoms are represented by single spheres. Spheres of the same size and colour represent atoms of the sameelement.

Molecules are represented by two or more spheres joined together.

Molecules of Elements are represented by two or more spheres of the same size and colour joinedtogether.

Molecules of Compounds are represented by two or more spheres of different sizes and colours joinedtogether.


Elements are composed of either atoms or molecules; molecules are formed only from atoms of thesame element. For example, a molecule of oxygen consists of two atoms of oxygen and has the chemicalformula O₂, where "O" is the chemical symbol of the element oxygen. Gases, except for noble gases, arediatomic molecules which means that there are two atoms for every molecule of gas.

Mixture consist of at least two different atoms or at least two different molecules. For example, amixture of neon and argon gases would consist of only the atoms of neon and argon because both neon andargon exist as atoms, rather than as molecules.

Compounds consist only of molecules, not individual atoms, and all the molecules of any onecompound are the same. For example, methane gas or carbon tetrahydride has the chemical formula CH₄.Each molecule of methane is formed from one atom of carbon, whose chemical symbol is "C", and fouratoms of hydrogen, whose chemical symbol is "H".

ACTIVITY 1: Match each diagram with its correct description. Diagrams will be used once.

_______ Pure element - only one type of atom present.

_______ Mixture of two elements - two types of uncombined atoms present.

_______ Pure compound - only one type of compound present.

_______ Mixture of two compounds - two types of compounds present.

_______ Mixture of a compound and an element.

LESSON 4: ATOMIC PARTICLES

Atoms are the basic building blocks of all matter.EVERYTHING on Earth is made of atoms...even the air and your body.

Protons (+)Neutrons (N)Electrons (e-)

Atoms

Atoms are made of three particles.

Positively charged particlesHelp make up the nucleus of the atomHelp identify the atom (could be considered an atom’s DNA)Equal to the atomic number of the atomContribute to the atomic massEqual to the number of electrons

Neutral particles; have no electric chargeHelp make up the nucleus of the atomContribute to the atomic mass

have a negative chargeorbit the nucleus of the atomare very small (have basically NO mass) in a neutral atom, there are the same number of protons and electrons

It is the electromagnetic force of attraction between the positive protons in the nucleus and the negative

Elements can be identified by their atomic number.The atomic number is the number of PROTONS in the atoms of an element.It can be used like a social security number for people.It is used to IDENTIFY the element from the Periodic Table.

The atomic mass number includes the number of protons and neutrons, since they are the two largestparticles in the atom.Since they are both located in the nucleus, the mass of the atom is located in the nucleus.Atomic Mass Number = protons + neutrons

Protons

Neutrons

Electrons

What force holds all the parts of an atom together?

electrons orbiting around the nucleus that holds the atom together.

Atomic Number

Elements contain one or more of the same type of atom. All known elements can be found on the periodic table.

Example: An element with 6 protons has an atomic number of 6 and is the element Carbon from the PeriodicTable.

Atomic Mass Number

Computing for the Number of Protons, Neutrons, and Electrons

Consider the following in computing for the number of protons, neutrons, and electrons

For uncharged (electrically neutral elements)

protons (p +) = electrons (e-) = atomic number mass number (atomic mass) = p + + n0neutron (n0) = mass number - atomic number = mass number - proton = mass number - electron

For charged elements (species)

protons (p +) = atomic number (but not electrons)e- = atomic number or proton number - charge ( a charge of positive implies losing of electrons and a charge of negative means gaining of electronsdepending on the number indicated in the charge)mass number (atomic mass) = p + + n0neutron (n0) = mass number - atomic number = mass number - proton = mass number - electron

For isotopes, the number of neutron is altered since the elements with isotopes have the same atomicnumber but different atomic masses.


ACTIVITY 1: Use the Periodic Table to complete the chart below.

Element Mass Number Protons Neutrons Electrons

1.Chlorine

2. Vanadium

3. Boron

4. Krypton

5. Cesium


LESSON 5: PERIODIC TABLE OF ELEMENTS

Periodic Table is a map of the building block of matter.Type: Metal, metalloid and Nonmetal

The elements in the Periodic Table are arranged in increasing atomic number as proposed by theEnglish experimental physicist Henry Moseley. Although Dmitri Mendeleev is often considered as the Fatherof the Periodic Table, the work of many scientists contributed to its present form.

A necessary prerequisite to the construction of the Periodic Table was the discovery of the individualelements. Although elements such as gold, silver, tin, copper, lead, and mercury have been known sinceantiquity, the first scientific discovery of an element occurred in 1669 when Hennig Brand discoveredphosphorus.

The Law of Triads

In 1817 the chemist Johann Dobereiner noticed that the atomic weight of strontium fell midwaybetween the weights of calcium and barium, two elements that possess similar chemical properties. This new idea of triads became a popular area of study. Between 1829 and 1858 the scientists JeanBaptiste Dumas, Leopold Gmelin, Ernst Lenssen, Max von Pettenkofer, and J.P. Cooke found that these typesof chemical relationships extended beyond the triad.

First Attempts at Designing a Periodic Table

The Periodic Table is regarded as an ordering of the chemical elements demonstrating the periodicityof chemical and physical properties.

Law of Octaves

John Newlands, an English Chemist, wrote a paper in 1863 which classified the 56 establishedelements into 11 groups based on similar physical properties, noting that many pairs of similar elementsexisted which differed by some multiple of eight in atomic mass.


Flammability - the ability to burn or ignite, causing fireToxicity - the quality of being poisonousRadioactivity - the ability to emit ionizing radiation or particlesHeat of combustion - the amount of heat released when the substance is completely burned. Reactivity with water - what happens when a substance reacts with water.Reactivity with acids - what happens when a substance reacts with an acid. Oxidation - the combination of oxygen with an element or substance, changing the appearance of theelement or substance.Corrosion - the deterioration of an element, usually metal, as a result of chemical reactions between itand its environment.

Chemical Behavior of Elements

Reactivity of Metals, Nonmetals, and Gases

The chemical elements can be categorized into metals, metalloids, and nonmetals according to theirshared physical and chemical properties. All metals have a shiny appearance and are good conductors ofheat and electricity.

Metalloids are metallic-looking brittle solids that are either semiconductors or exist insemiconducting forms, and have amphoteric or weakly acidic oxides.

Nonmetals display the characteristics of being dull, colored or colorless in appearance; are brittlewhen solid; are poor conductors of heat and electricity and have acidic oxides.

Most of some elements in each category share a range of other properties.

Importance of the Elements

Elements are naturally occurring and are sporadically distributed in the Earth's Crust. More than 30elements help plants and animals to survive.

The human body uses diverse chemical elements for diverse functions. One specific example iscalcium. Your body needs calcium to build strong bones and fluorine to make your teeth healthy. As yourbody consumes these elements through daily functioning you need to replace them in order for you to syathealthy and strong.

From hydrogen to lawrencium to carbon to gold, there are a total of 115 known elements thatcomprise all tangible matter.

ACTIVITY 1: Write your answer on the blank provided.

_______________________________ 1. It is a map of the building block of matter.

_______________________________ 2. It is classified the 56 established elements into 11 groups based on similar physical properties

_______________________________ 3. It is the ability to burn or ignite, causing fire

_______________________________ 4. It is the combination of oxygen with an element or substance, changing the appearance of the element or substance.

_______________________________ 5. It is the quality of being poisonous

_______________________________ 6. It is a metallic-looking brittle solids that are either semiconductors or exist in semiconducting forms, and have amphoteric or weakly acidic oxides.

_______________________________ 7. It is the ability to emit ionizing radiation or particles

_______________________________ 8. It display the characteristics of being dull, colored or colorless in appearance

_______________________________ 9. It is categorized into metals, metalloids, and nonmetals according to their shared physical and chemical properties.

_______________________________ 10. It is the deterioration of an element, usually metal, as a result of chemical reactions between it and its environment.

science grade 8 (unit 1) - drcilearn.com

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