Grade 9 Pre-IB Science - Unit 1 Chemistry

Hands may get more dry in winter because __________ in the air decreases.

less water vapour

The flame of a bunsen burner turns from orange to blue when __________ is added.

more oxygen

Examples of plasma include __________ and some things in space such as quasars.

Aurora Borealis

The __________ is the lowest energy state of electrons in an atom.

ground state

Physical changes, such as ice freezing or melting, do not change the __________ of a substance.

molecular structure

Bose-Einstein condensation occurs at __________ temperatures.

extremely low

The signs of a __________ change include a new smell, new colour, and the formation of bubbles.

chemical

An element that cannot be broken down further is defined as a __________.

pure substance

Significant digits are the numbers between __________ that are always considered significant.

1-9

When rounding numbers, if the digit before 5 is even, it remains the __________.

same

To convert from grams to kilograms, you divide by __________.

1000

Density is calculated using the formula __________.

mass / volume

The __________ of a substance reflects how well it sticks to itself.

cohesion

The atomic number of an element is equal to the number of __________ it has.

protons

If an atom gains electrons, its ion charge becomes __________.

negative

When electrons absorb energy and move to a higher energy level, they are in an __________ state.

excited