Science Grade 9 Exam

What are the 3 components of an atom?

Proton (+), Neutron (neutral), and electron (-)

What did Democritus propose?

Stated that atoms could be broken down into a size indestructible particle, which he called “atomos”.

What is the meaning of “Atomos”?

Uncuttable

What did Aristotle propose?

Believed that all matter is made up of four basic elements: earth, air, fire, and water. Was proven WRONG.

What did John Dalton propose?

Matter is made up of small particles called atoms

What did JJ Thomson propose?

Electrons exist!

What did JJ Thomson’s model look like?

“Plum Pudding”: pudding \= positive massplums \= negative charges floating in mass.

Which scientist did the gold foil experiment?

Ernest Rutherford

How did the gold foil experiment work?

Shot alpha particles at a thin gold foilExpected the particles to pass throughSome particles deflected at large angles

What did the experiment discover?

The experiment concluded that atoms have a small, dense, positively charged nucleus in the centre

What did Neils Bohr propose?

Discovered how the electrons orbit the nucleus, gaining or losing energy depending on how far they are from it.

What did James Chadwick propose?

Existence of neutrons!

What does the atomic number tell us about an atom?

The number of protons in the atom, and which element it is.

How do you find your number of neutrons?

Atomic mass - atomic number

What is the charge of a proton?

+1

What is the charge of a neturon?

0

What is the charge of an electron?

-1

What is the mass of a proton?

1 atomic mass units (amu).

What is the mass of an electron?

Virtually 0 atomic mass units (amu).

What is the mass of a neutron?

1 atomic mass units (amu).

What is the role of a proton?

Uniquely defines the element.

What is the role of a neutron?

Holds the nucleus together.

What is the role of the electron?

Shows the reactivity of an element and its ability to bond with other elements.

What is the family name of group 1 on the periodic table?

Alkalai metals

What is the family name of group 2 on the periodic table?

Alkaline earth metals

What is the family name of group 17 on the periodic table?

Halogens

What is the family name of group 18 on the periodic table?

Noble gases

What happens to the mass as you move from left to right on the periodic table?

The mass generally increases.

What does the period number tell us about an atom?

Number of orbitals (energy level)

What does the group number tell us about an atom?

Number of valence electrons

What happens when you change the number of protons in an atom?

It becomes a different element

What do you have when you change the number of neutrons? What specifically changes?

Forms an ISOTOPE. The mass of the atom will change.

What happens when you change the number of electrons?

The atom becomes an ION.

What is the name of an atom that GAINS electrons and becomes NEGATIVE?

Anion

What is the name of an atom that LOSES electrons and becomes POSITIVE?

Cation

What are properties of metals?

Shiny/metallic lustre

High melting point

Good electricity conductors

Good conductors of heat

Malleable

Ductile

What are properties of nonmetals?

Dull lustre

Low melting point

Poor electricity conductors

Poor conductors of heat

Brittle (not malleable)

Not ductile

What are properties of metalloids?

Shiny OR dull

Can be malleable and ductile but not always

“Okay” conductor of electricity or heat

How does reactivity of metals change as you move down the group?

It INCREASES

How does reactivity of metals change as you move LEFT to RIGHT across periods?

It DECREASES

Ionic bonds form between…

Metals and nonmetals

Covalent bonds form between

Nonmetals

A charged atom due to the loss or gain of one or more valence electrons.

Ion

An atom with 6 valence electrons would need \______ more to become stable

2

These elements have 8 valence electrons so they already are stable.

Noble gases

How many electrons does an atom want to have in its outer shell?

8

What is the charge of an atom that has lost two electrons?

2+

What is the charge of an atom that has lost three electrons?

3+

What is the charge of an atom that has gained three electrons

3-

When this atom gains one valence electron what will its charge be?

1-

States that atoms will lose gain electrons in order to acquire a full set of eight valence electrons and become stable

octet rule

An atom with 5 valence electrons would need \______ more to become stable

3

An atom with 7 valence electrons would need \______ more to become stable

1

How do you know which element will come first in a compound?

The element that comes first in a compound is the one that shows up in a group with a lower number.

Which Element would come first in a compound: Oxygen (8) or Magnesium (12)

Mg

Which Element would come first in a compound: Lithium (3) or Silicon (14)

Li

Which Element would come first in a compound: Iron (26) or Bromine (35)

Fe

Which Element would come first in a compound: Carbon (6) or Indium (49)

In

Amps

unit of current

current electricity

The rate at which electrons flow within a circuit

Voltage

The potential difference measured in volts. The amount of work to be done to move a charge from one point to another along an electric circuit.

Volts

Unit for electric potential difference

Voltmeter

instrument that measures potential difference

ammeter

instrument used to measure current

series circuit

A circuit in which all parts are connected end to end to provide a single path of current.

parallel circuit

A closed circuit in which the current divides into two or more paths before recombining to complete the circuit

resistance

A material's opposition to the flow of electric current.

electrical energy

Energy made available by the flow of electric charge through a conductor; equal to power x time

high resistance due to large length and small Area

Resistance of long, thin wire

low resistance due to small length and large Area

Resistance of short, fat wire

power source

Provides the voltage for the circuit.

load

the materials carried by a stream

lamp

light source

Conducting wire (conductor)

allows electrons to flow freely based on their loose hold of valence electrons

electric circuit

a complete, unbroken path through which electric charges can flow

series circuit

A circuit in which all parts are connected end to end to provide a single path of current.

parallel circuit

A circuit that contains more than one path for current flow.

current

A flow of electric charge.

Amps (A)

The unit of measurement for current (amount of charge/sec)

Charge

A measure of the extra positive or negative particles that an object has.

electrons

negatively charged particles

ammeter

A device used to measure current in a circuit

Voltmeter

A device used to measure voltage, or electrical potential energy difference

potential difference (voltage)

the difference between the electric potential energy per unit of charge at two points in a circuit

Resistance

the characteristic of a material that slows electron flow

resistor

An electrical device that resists the flow of electrical current

Ohms law

V\=IR

circuit open

device off

circuit closed

device on

how to measure voltage

voltmeter connected in parallel

Current symbol

I

Current unit

amperes

Current formula

V/R

voltage unit

Volts

Resistance formula

V/I

Resistance unit

Ω

A load had 2 A of current flowing through it. The voltage across the load is 6.0 V. Calculate the resistance

R \= V/I R \= 6.0/2 R \= 3.0 Ω

A 12 ohm resistor is connected to a power supply set at 6 V. Calculate the current going though the resistor

I \= R/V I \= 12/6 I \= 2 amperes

Resistance formula

R\= V/I

Voltage formula

IxR