Grade 9 Science Flashcards
Matter
Is anything that has mass and volume(takes up space), also made up of particles
Physical Property
A characteristics of a substance that can be determined without changing the composition of the substance
Example: Color,Texture, Flexibility, Clarity, Ductility, Color, Texture, Flexibility, Clarity, Ductility, Form, Amorphous, Lustre, Hardness, Physical state, Brittleness, Weight, Height, Length, Mass, Size, Volume, Melting point, Boiling point
Chemical Property
A characteristic of a substance that is determined when the composition of the substance is changed and one or more new substances are produced
Example: Combustibility, Dissolving, Reactions with acids, Solubility
Qualitative Property
a property of a substance that is not measured and does not have a numerical value, such as colour, odour, and texture
Example: Ductility, Form, Amorphous, Lustre, Hardness, Color, Texture, Flexibility, Clarity, Physical state, Brittleness
Quantitative Property
a property of a substance that is measured and has a numerical value, such as temperature, height, and mass
Example: Mass, Size, Volume, Melting point, Boiling point, Weight, Height, Length
Pure substances:
anything that consist of only 1 type of particles (atoms or molecules)
Example: tin, sulfur, diamond, water, pure sugar (sucrose), table salt (sodium chloride) and baking soda
Element
An element is a pure substance that is made from a single type of atom.
Example: Hydrogen, Carbon, Nitrogen, Sodium, Potassium, Aluminium, Sulphur, Oxygen, Neon, Zinc, Copper, Iron, Mercury, Chlorine, Radium, Gold, Silver
Compound:
All of the same kind of molecule made up of different types of atoms.
Example: water, carbon dioxide
Mixture:
In chemistry, a mixture is a material made up of two or more different substances which are physically combined.
Examples: Air, ice cubes in a drink, sand and water, and salt and oil.
Characteristic Physical property:
A physical property that is unique to the substance and can be used to identify the substance.
Example: freezing/melting point, boiling/condensing point, density, viscosity and solubility.
Homogeneous:
The different types of particles in a substance are distributed uniformly.
Heterogeneous:
The different types of ingredients in a substance are visible.
Mechanical mixture:
Is when two or more different materials are mixed together but are visible.
Example: sand and stones on a beach or milk in cereal in a bowl
Suspension:
A heterogeneous mixture in which solute-like particles settle out of a solvent-like phase sometime after their introduction.
Example: chalk and water, muddy water, the mixture of flour and water, a mixture of dust particles and air, fog, milk of magnesia
Atom:
Is the smallest component of an element, characterized by a sharing of the chemical properties of the element and a nucleus with neutrons, protons and electrons.
Molecule:
Molecules are made up of different atoms that are held together by chemical bonds
Solution:
Different molecules that look like the same substance; substance is clear/transparent
Example: Salt water, rubbing alcohol, and sugar dissolved in water
Colloid:
Different molecules that look like the same substance; substance is opaque
Example: whipped cream, mayonnaise, milk, butter, muddy water, plaster, colored glass, and paper.
Alloy:
A mixture of metal
Proton:
A subatomic particle that is energy, located in the nucleus of an atom and has a positive charge. Found by the atomic number
Neutron:
A subatomic particle that is considered energy, located in the nucleus of an atom that has a neutral charge. Found by subtracting mass number by the atomic number
Radioisotope:
A version of a chemical element that has an unstable nucleus and gives off radiation in the process of stable form.
Electron:
A subatomic particle that is considered energy, located on spherical shells called orbitals and they have a negative charge. Equal to the atomic number/ # of protons
Polyatomic Ions:
Ions that consist of more than one atom.
Ionic Compound:
Ionic Compound made between metals and non-metals. When an electron goes from one atom to the other atom.
Covalent Compound:
When two nonmetals share electrons in the valence shell.
Periodic Table:
Is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The inventor was Dmitri Mendeleev.
Group/Families:
The columns, called groups, contain elements with similar chemical behaviours.
Periods:
Rows are referred to as periods which identity the number of shells.
Atomic Number:
Indicates the number of protons in the nucleus
Atomic Mass:
The atomic mass is the mass of a single atom of the element.
Mass Number:
The number of protons and neutrons in the atom’s nucleus.
Isotope:
Is when the number of neutrons is different (that is, a greater or lesser atomic mass) than the standard for that element.
Ion:
A particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons Hyponyms: anion, cation.
Valence Shell:
the outermost shell of an atom containing the valence electrons
Valence electrons:
The electrons located in the outermost (valence) shell of an atom
Cations:
A metal ion that carries a positive charge
Anion:
A non-metal ion that carries a negative charge
Chemical formula:
It contains the symbols of the atoms of the elements present in the compound as well as how many there are for each element in the form of subscripts.
Physical Change:
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition.
Examples: Crushing a can, Melting ice cube, Boiling water, Breaking a glass, Shredding paper, Chopping wood.
Chemical Change:
A chemical change is a chemical reaction involving the rearrangement of atoms.
Examples: Cooking an egg, Heating sugar to form caramel, Baking a cake, Rusting of iron.
Chemical change Signs:
- Color Change
- Production of an odor
- Change of Temperature
- Evolution of a gas (formation of bubbles)
- Precipitate (formation of a solid)
The Particle theory of matter
- All matter is made up of tiny particles that have empty spaces between them.
- Different substances are made up of different kinds of particles.
- Particles are in constant random motion
- The particles of a substance move faster as its temperature increases.
- Particles attract each other
Democritus (6)
- (around 400 BCE)
- Greek Philosopher
- Discovered the smallest unit of an element; an Atom
- Atoms were in different sizes
- Atoms were in constant motion
- Separated by empty space
Aristotle (4)
- (around 450 BCE)
- Greek Philosopher
- Matter is made up of four basic substances; earth, water, air, fire
- This theory was accepted for almost 2000 years
John Dalton (8)
- (1807)
- English scientist and teacher
- Proposed that:
All matter is made up of tiny invisible particles called atoms - All atoms are identical
- Atoms of different element are different
- Atoms are rearranged to form new substances in chemical reactions
- atoms are never created or destroyed
- Could not explain why some objects attracted, while others repel
J.J Thompson (6)
- 1897
- Discovered Electrons
- He concluded that atoms contain negatively charged electrons
- Since atoms are neutral, the rest of the atom is a positively charged sphere
- Negatively charged electrons are evenly distributed through the atom
- Plum Pudding/ Chocolate Chip muffin model
Ernest Rutherford (6)
- (1909)
- Gold Foil Experiment
- Discovered Proton and Nucleus
- Revised model;
Centre which is the nucleus has a positive charge and takes up very less space in the atom
5.Nucleus is surrounded by a cloud of negatively charged electrons - Most of the atom is empty space
THE GOLD FOIL EXPERIMENT Purpose (4)
- (1909)
- To Test Thomson’s model of an atom
- Predicted that if positive and negative charges were uniformly distributed throughout, then tiny positively charged particles shot at a thin piece of gold foil would pass through
- Although some might be slowed down or deflected at small angles
THE GOLD FOIL EXPERIMENT Set up (4)
Gold Foil in the centre, Detecting screen around it, an open slit in the middle for the particles to pass
THE GOLD FOIL EXPERIMENT Result (2)
- During the experiment most particles went straight through, but some deflected at very large angles
- Rutherford believed that the deflection was caused by a collision with a small, concentrated, positively charged central mass inside the atom (nucleus)
James Chadwick (9)
- (1932)
- Discovered Neutrons
- Neutrons don’t have a charge
- Proposed that;
Atom is empty, with a dense central nucleus - Nucleus has positively charged protons and no charged neutrons
- Mass of neutron and proton is the same
- Negatively charged electrons circle rapidly around the nucleus
8.Neutron atom has the same number of protons and electrons - Planetary model
Niels Bohr (7)
- (1913)
- Danish Scientist that studied the hydrogen atom and light
- Only a few colors show when a prism is shown through hydrogen
- Bohr proposed in 1913 that electron has a definite amount of energy
- The farther the electron is from the nucleus, the greater the energy
- Electrons cannot be between orbits, they can jump between orbits and that produces light
- Each orbit holds a certain number of electrons
Electricity
a form of energy that results from the interaction of charged particles, such as electrons or ions. It is a form of energy and the movement of electrons.
Series
The flow of electrons follows only one path
Parallel:
The flow of electrons can flow more than one way
Direct current (DC)
Direct current flows in one direction and electronic devices use DC. (Direct current does not switch directions)
Alternating Current (AC)
Electrons move back and forth, changing their directions which causes a “domino effect”. Moving Magnet in and out of coiled wire.
Electric Charge
equal to the quantity of electricity carried in one second by a current of one ampere. Measured in coulombs and variable is Q.
Time-
Measured in seconds
Resistors
An electrical component that limits or regulates the flow of electrical current in an electronic circuit.
Current
a flow of electric charge. Measured in amperes and variable is I.
Conductors
usually, metals that allow electrons to move between atoms. Copper, aluminum, tap water (dissolved ions), silicon.
Voltage (potential difference)
the difference in electric potential energy per unit charge measured at two different points. Measured in volts and the unit is V.
Resistance
The ability of a material to oppose the flow of electric current. Measured in ohms (Ω) and the unit is R.
Insulator
A material or an object that does not easily allow electricity to pass through.
Short circuit
a problem in an electrical circuit where two or more wires are not supposed to come in contact with each other touch.
Semi-Conductor
A material that is neither a good conductor of electricity nor a good insulator, but has properties of electrical conductivity somewhere between the two.
Power
how fast energy can be changed into work.
Ammeter
a device used to measure current
Voltmeter
a device used to measure voltage
Electrical energy generation
the process of generating electric power from sources of primary energy.
Electric potential difference
the difference in electric potential (V) between the final and the initial location when work is done upon a charge to change its potential energy.
Load
the portion of a circuit that consumes electric power.
Three sources of dc:
Primary cell, secondary cell and fuel cell
Primary cell:
Primary cells are batteries that cannot be charged and used again because the chemical reactions that produce a flow of electrons are irreversible.
Secondary cell:
electric cells that can be recharged and used many times before recycled.
Fuel cells (3):
A fuel cell is a device that converts chemical potential energy (energy stored in molecular bonds) into electrical energy. A PEM (Proton Exchange Membrane) cell uses hydrogen gas (H2) and oxygen gas (O2) as fuel. The products of the reaction in the cell are water, electricity, and heat.
How does a fuel cell work:
A fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. At the cathode, the protons, electrons, and oxygen combine to produce water molecules. Due to their high efficiency, fuel cells are very clean, with their only by-products being electricity, excess heat, and water.
How does a battery work:
When a device is connected to a battery — a light bulb or an electric circuit — chemical reactions occur on the electrodes that create a flow of electrical energy to the device. … Meanwhile, at the positive terminal, the cathode accepts electrons, completing the circuit for the flow of electrons.
Electricity (2)
a form of energy that results from the interaction of charged particles, such as electrons or ions. It is a form of energy and the movement of electrons.
Static electricity (3)
an imbalance of electric charges within or on the surface of a material.
Static electricity is created by applying friction force between two objects. The friction force transfers electrons from one object to the other
Electric current
are electrons in motion along a path, regardless of the number of electrons flowing.
Electroscope:
An electroscope is an early scientific instrument used to detect the presence of electric charge on a body
triboelectric/ electrostatic series
a list that ranks various materials according to their tendency to gain or lose electrons.
Law of Electric Charges (3)
Things that have the same charge push each other away (they repel each other). This is called the Law of Charges. Things that have more electrons than protons are negatively charged, while things with fewer electrons than protons are positively charged. Things with the same charge repel each other.
Friction
a force that holds back the movement of a sliding object.
Conduction
transfer of energy through the movement of particles that are in contact with each other
Induction
refers to the transfer of energy through the movement of particles without contact
grounding / grounding wire
refers to a connection to the earth, which acts as a reservoir of charge
Conductor
an object or type of material that allows the flow of charge, usually metals
Insulator
A material or an object that does not easily allow electricity to pass through (Ex. Styrofoam, paper, glass
Conduction
When charging by contact (conduction) occurs, one object is already electrically charged. The other object may or may not be charged as well.
Induction (without touching) (2)
This charge separation occurs if the electrons move within an object so one side has a more negative charge than the other. This can be done permanently if a grounding wire is connected and then is cut off, so the electrons can not travel back.
