chemical change

Question 1

difference between elements and compounds? provide examples

Answer 1

Element is a pure substance made of 1 type of atom, arranged on periodic table (oxygen, hydrogen, gold). Compound is 2 or more different elements chemically bonded (eg water)

Question 2

2. Define the term atom and state what it mostly made up of.

Answer 2

Smallest particles of matter made up mostly of space.

Question 3

3. List the 3 sub-atomic particles, their charges and where each is found in an atom.

Answer 3

Protons are positive and found in the nucelus, neutrons don’t have a charge and are found in the nucleus and finally, electrons are negatively charged and found around the atom in the rings called shells

Question 4

5. Explain why an atom is considered to be electrically neutral.

Answer 4

The positive charge from protons and negative charge from electrons cancel eachothers charge out

Question 5

6. Describe how atoms are arranged in the periodic table.

Answer 5

According to their size (smallest at start and largest at end)). theyre also arranged in metals on left and non metals on right. there are horizontal rows called periods and vertical columns called groups.

Question 6

atomic number

Answer 6

number of protons an element has

Question 7

mass number

Answer 7

number of both the protons and neutrons in an atom

Question 8

properties of metals

Answer 8

Good conductors of heat
good electrical conductors and shiny, high melting point, malleable

Question 9

non metals

Answer 9

poor thermal conductors and electrical conductros. not malleable or ductile. dull, not metallic and gain electrons easily

Question 10

only metal thats liquid at room temp?

Answer 10

mercury

Question 11

metalloids? give examples

Answer 11

conduct a bit of electricity, show proterties of both metal and non metal eg silicon, boron, geranium, arsenic.

Question 12

difference between a physical and a chemical change

Answer 12

Physical, no new substance are produced and in chemical, new substances are formed

Question 13

examples of a physical change

Answer 13

Ice melting, paint mixed, can being curshed

Question 14

chemical reaction examples

Answer 14

photosynthesis, rust, baking, digestion

Question 15

4 signs of a chemical reaction

Answer 15

Precipitate/solid formed, colour change, gas produced (bubbles), energy in form of heat, sound or light

Question 16

four factors that can change the rate of a reaction

Answer 16

particle size, temperature, concertation of substance, presence of catalyst

Question 17

how is temperature used to increase the rate of a reaction

Answer 17

heat energy is added so particles gain kinetic energy causing them to move quicker and more likely to collide.

Question 18

how is concentration used to increase the rate of a reaction

Answer 18

concentration is how many particles of one type there are in 1 area. more concentrated substances react easier cuz of higher collision chance

Question 19

how are catalysts used to increase the rate of a reaction

Answer 19

catalysts are remained unchanged after reaction. they temporarily bind with reactants providing them with correct orientation for collision.

Question 20

how is particle size used to increase the rate of a reaction

Answer 20

the smaller the particle is, the more surface area it has and the more likely collision is to occur.

Question 21

mixture

Answer 21

contains 2 or more substances not chemically bonded together. eg saltwater made of salt (NaCl) and water (H2O)

Question 22

molecule