Chemistry

Question 1

Classifying matter:

Answer 1

• all matter is made up of extremely tiny particles
• each pure substance has its own kind of particle, different from other particles
• always moving
• attract
• high temp particles=moves fast

Question 2

Attractive forces are:

Answer 2

weakest in gases
stronger in liquids
strongest in solids

Question 3

What is heterogeneous and homogeneous mixture?

Answer 3

• homogeneous= particles are uniformly mixed

- heterogeneous=particles are uniformly scattered

Question 4

matter is broken into two parts what are they?

Answer 4

pure substance and mixtures

Question 5

what are the 4 types of heterogeneous mixtures we learned about, and how are they described?

Answer 5

• ordinary mechanical mixtures= can see parts (ex granite)
• suspension= uniformly mixed, but will settle (ex flour or chalk)
• colloids= fine particles evenly distributed throughout a second substance (ex hair gel, clouds)
• emulsion= colloids that have liquids dispersed in liquids (ex, mayo, milk, salad dressing)

Question 6

Changes in matter (difference between chemical and physical change)

Answer 6

• physical change= changes form, but no new substance is formed (ex cutting an orange)
• chemical change= causes one or more news substances to be formed=impossible to reverse (ex burning paper)

Question 7

What can be observed or messured?

Answer 7

-any property that can be observed or measured without forming a new substance= physical change

Question 8

what are properties to classify if chemical or physical:

Answer 8

• if it has color=chemical
• density=physical
• if element is combustible= chemical

Question 9

physical properties can be further classified as?

Answer 9

• qualitative= characteristic of a substance that cannot be measured, but can be described
• quantitative=characteristic of a substance that can be measured

Question 10

element=?

Answer 10

pure substance

Question 11

What is the law of conservation of mass?

Answer 11

In a chemical charge, the total mass of the new substance is always the same as the total mass of the original substances.

Question 12

What is a compound?

Answer 12

compounds are pure substances that contain two or more elements combined together in fixed or definite proportions.

Question 13

what is daltons atomic theory?

Answer 13

• all matter is made of small particles called atoms
• atoms cannot be created destroyed or divided
• all atoms of the same element are identical in size and mass
• compounds are created when atoms of different elements link together in definite proportions

Question 14

What are all the atomic models dates and creators?

Answer 14

• plum pudding-JJ Thomson 1897=reasoned that there must be positively charged particles in atom
• Ernest Rutherford 1911=thought that the mass of an atom must be found in the centre= named it atomic nucleus
• Niels Bohr 1913= both Rutherford and Bohr believed the atom is like a solar system with the electrons circling around the nucleus
• Louis De Broglie, today= was an area around the nucleus that contains electrons

Question 15

what is electrons, protons, and neutrons charges?

Answer 15

• proton=positive
• electron= negative
• neutron=neutral

Question 16

what are the 5 main groups in the periodic table?

Answer 16

• alkali metals= very reactive
• alkaline earth metals= not very reactive
• noble gases= very un-reactive
• the halogens=reactive with almost any element
• transition groups

Question 17

All about the periodic table:

Answer 17

• created by Dmitri Mendeleev
• atomic number= the number of protons an element has in its nucleus
• atomic mass=total number of protons and neutrons
• metals mostly on left besides hydrogen
• non-metals=right side of staircase
• metalloids= staircase
• horizontal rows=periods
• vertical rows=groups

Question 18

What is the difference between ionic and molecular compounds

Answer 18

• ionic compounds= atoms that transfer electrons

- molecular compounds= atoms that share electrons

Question 19

What is a chemical formula?

Answer 19

-uses numbers and symbols to represent the composition of a pure substance

Question 20

what is a molecule?

Answer 20

-is the smallest independent unit of a pure substance, and is generally a cluster of atoms.

Question 21

what is a diatomic molecule?

Answer 21

-molecules made up of 2 atoms of the same element

Question 22

ionic:

Answer 22

• formed from metallic and non-metallic elements
• forms ions in solution
• conducts electricity
• solid at room temp

Question 23

molecular:

Answer 23

• formed form only non-metallic element
• does not form ions in solution
• does not conduct electricity
• solid, liquid, or gas at room temp

Question 24

writing molecular compounds:

Answer 24

1. write first element
2. change the ending to ide
3. use prefixes to indicate the number of each type of atom (only second element)
   Mono=1
   di=2
   tri=3
   tetra=4
   penta=5
   hexa=6
   hepta=7
   octa=8
   nona=9
   deca=10

Question 25

symbol for molecular:

Answer 25

1. write symbols for elements in order that appear | 2. use subscripts to indicate number of each type of element

Question 26

naming ionic compounds:

Answer 26

1. the name includes both names of the element in compound, metallic element first 2. non-metallic element second and ending is changed to ide 3. subscripts indicate ratio of ions

Question 27

What is a chemical reaction?

Answer 27

-two or more substances udergo a reorganization of atoms and form other substances

Question 28

What is the difference between reactants and products?

Answer 28

reactants= the substances that go into the reaction | products=the substances that are produced after a reaction

Question 29

What is the difference between exothermic and endothermic?

Answer 29

- exothermic=chemical reactions that give off heat | - endothermic=chemical reactions that absorb energy

Question 30

what is the reaction rate?

Answer 30

-how fast a reaction occurs

Question 31

what is a catalyst?

Answer 31

- a substance that speeds the rate of the reaction without changing itself - does not affect the amount of product produced

Question 32

What is an enzyme?

Answer 32

- a natural catalyst made of living things

Question 33

What is an inhibitor?

Answer 33

-substance that slow down chemical reaction

Question 34

Which reactions can be reversed and which ones cannot?

Answer 34

- chemical changes are impossible to reverse | - physical changes can be reversed, because their properties are temporary

Question 35

How can elements be classified into their families?

Answer 35

- by their properties

Question 36

What are the properties of metals, non-metals and metalloids?

Answer 36

- metals=shiny appearance and solid at room temp - non- metals= not shiny, solid gas or liquid at room temp - metaloids= have products in between