Year 9 Science CT1 Revision

Includes the first topic, such as atoms, molecules, etc.

What is an atom?

The smallest particle that can be obtained by chemical means.

What are the three subatomic particles?

proton, neutron, electron

Where are protons and neutrons located in an atom?

in the nucleus

Where are electrons located in an atom?

in shells (energy levels) around the nucleus

What is the charge of a proton?

positive (+1)

What is the charge of a neutron?

neutral (0)

What is the charge of an electron?

negative (-1)

What is the relative mass of a proton?

1

What is the relative mass of a neutron?

1

What is the relative mass of an electron?

almost 0

Why is an atom electrically neutral?

because it has equal numbers of protons and electrons

What is the nucleus of an atom made of?

protons and neutrons

What is the atomic number?

the number of protons in an atom

What is the mass number?

the number of protons plus neutrons in an atom

How do you calculate the number of neutrons?

mass number minus atomic number

What is the electron configuration for the first 20 elements based on?

shells holding 2, 8, 8 electrons

What is a valence electron?

an electron in the outermost shell of an atom

Who first proposed that all matter is made of atoms?

Democritus

Who agreed that matter is made of indestructible atoms?

John Dalton

Who proposed the plum pudding model?

J.J. Thomson

Who discovered the nucleus using the gold foil experiment?

Ernest Rutherford

Who showed that electrons orbit in different energy levels?

Niels Bohr

Who discovered the neutron?

James Chadwick

What is an element?

a substance made up of only one type of atom

How many known elements are there as of 2016?

118

How many elements occur naturally on Earth?

98

What is the periodic table?

an arrangement of elements by increasing atomic number

Who is credited with creating the first useful periodic table?

Dmitri Mendeleev

What did Mendeleev predict about undiscovered elements?

their existence and properties

What is a group on the periodic table?

a vertical column

What is a period on the periodic table?

a horizontal row

What does the group number tell you (for groups 1-8)?

the number of valence electrons

What does the period number tell you?

the number of electron shells

Where are metals located on the periodic table?

on the left and middle

Where are non-metals located on the periodic table?

on the right

Where are metalloids located?

along the zigzag line between metals and non-metals

What are the alkali metals?

Group 1 elements

What are the halogens?

Group 7 elements

What are the noble gases?

Group 8 (or 0) elements

What is the trend in reactivity down Group 1?

increases

What is the trend in reactivity down Group 7?

decreases

Why are noble gases unreactive?

they have a full outer shell of electrons

At room temperature, most metals are in which state?

solid

Which two elements are liquids at room temperature?

mercury (Hg) and bromine (Br)

Name the only metal that is liquid at room temperature.

mercury

What state are noble gases at room temperature?

gas

What is an isotope?

atoms of the same element with different numbers of neutrons

Do isotopes have the same number of protons?

yes

Do isotopes have the same mass number?

no

What is an ion?

an atom that has gained or lost electrons

Why do atoms form ions?

to obtain a full outer shell

What is a positive ion called?

cation

What is a negative ion called?

anion

What is a molecule?

two or more atoms joined together

What is a compound?

a substance made of different kinds of atoms bonded together

What is a mixture?

two or more substances mixed but not chemically combined

Can the components of a mixture be separated by physical means?

yes

Is water an element, compound, or mixture?

compound

Is air an element, compound, or mixture?

mixture

Is oxygen gas (O₂) an element or compound?

element

What is a physical property?

a feature that can be observed without changing the substance

What is a chemical property?

a feature that describes how a substance changes in a chemical reaction

Give an example of a physical property.

melting point, conductivity, color

Give an example of a chemical property.

flammability, reactivity with acid

What is the law of conservation of energy?

energy cannot be created or destroyed, only transferred

What is the independent variable in an experiment?

the variable you change on purpose

What is the dependent variable in an experiment?

the variable you measure

What are controlled variables?

variables kept constant to ensure a fair test

Why do we wear safety glasses in the lab?

to protect eyes from chemicals and broken glass

What should you do with long hair in the lab?

tie it back

What is the first step in lighting a Bunsen burner?

close the air hole

Why do you close the air hole when lighting?

to produce a visible safety flame

What color is the safety flame?

orange

What color is the hottest flame?

blue

How do you get a blue flame?

open the air hole

What is the function of the air hole on a Bunsen burner?

to control the amount of oxygen mixing with gas

What equipment would you use to measure a volume of liquid accurately?

measuring cylinder or pipette

What is a beaker used for?

holding, mixing, or heating liquids

What is a test tube used for?

holding small amounts of substances

What is a tripod used for?

supporting apparatus over a Bunsen burner

What is a gauze mat used for?

spreading heat evenly under a container

What is a funnel used for?

transferring liquids or filtering

What is the atomic number of hydrogen?

1

What is the atomic number of helium?

2

What is the atomic number of lithium?

3

What is the atomic number of carbon?

6

What is the atomic number of nitrogen?

7

What is the atomic number of oxygen?

8

What is the atomic number of fluorine?

9

What is the atomic number of neon?

10

What is the atomic number of sodium?

11

What is the atomic number of magnesium?

12

What is the atomic number of aluminum?

13

What is the atomic number of silicon?

14

What is the atomic number of phosphorus?

15

What is the atomic number of sulfur?

16

What is the atomic number of chlorine?

17

What is the atomic number of argon?

18

What is the atomic number of potassium?

19

What is the atomic number of calcium?

20