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Answer the following four questions in complete sentences:1. Are the assessment reflections a useful tool? Why

or why not?

2. On a scale from 1-10, how well do the assessment reflections help prepare you for the next quiz/exam?

3. What is one change that you would implement to make the process more useful?

What is an element?Mr. HeffnerChemistry

9/15/09

What is matter?

Stuff!

Elements

What is an element?An element is…

pure substance that is made up of only one type of atom

An element has…a unique set of physical and chemical properties

Examples of elements:GoldHeliumSodium

What is an element?

What is an element?“…one type of atom”?

Every atom of an element has the same number of protons

Atomic number is…The number of protons in an atom

So put another way, every atom of a specific element has the same atomic number!

SummaryMatter elements atoms

Elements are pure substances made up of atoms that have the same atomic number

Atomic number = # of protons

FoldableFold in half 3X, then unwrap and fold in windows

Cut with scissors 3 hole-punch

Terms: only 4!ElementPeriodic Table of Elements (mini-picture)Proton (charge, mass, location)Atomic number

Quiz yourself when finished

What is an element?Element is represented by a box on the periodic

table

1

HHydrogen

What is an element?

1

HHydrogen

Atomic number

Symbol

Name

What is an element?

79A

uGold

Atomic number

Symbol

Name

What is an element?The periodic table is organized by atomic

number

Trend: a general rule that is followed

Trend in atomic number INCREASES from Left to Right INCREASES from Top to Bottom

What is an element?Which of the following has a higher atomic

number?C (Carbon) or N (Nitrogen)?C (Carbon) or Si (Silicon)?C (Carbon) or Ge (Germanium)?

SummaryElements are represented as boxes on the

periodic tableAtomic number is found above the symbol

The periodic table is organized by increasing atomic number

Practice Questions Answer the following in complete sentences:

1. What is the definition of an element?

2. Are atoms of an element the same of different?

3. What is atomic number?

4. Draw and label the representation of N (Nitrogen).

5. What is the atomic number of He (Helium)?

6. What is the atomic number of Cl (Chlorine)?

7. What is the trend in atomic number?

Exit Slip1. All atoms of an element have

a. the same number of protons.

b. the same number of neutrons.

c. the same number of electrons.

d. neither mass nor volume.

2. Which of the following is true for atomic number?a. it is what defines an element

b. it is the sum of all the protons in an atom’s nucleus

c. it can be found on the periodic table

d. all of the above

Exit Slip3. What is the atomic number of F (Fluorine)?

a. 1

b. 9

c. 19

d. 19.00

4. How does atomic number vary throughout the periodic table?a. it is fixed and does not change as you move across the

periodic table

b. it decreases from left to right, and from top to bottom

c. it increases from left to right, and from top to bottom

d. it increases from right to left, and from top to bottom

Exit Slip5. Which element has a smaller atomic number

than O (Oxygen)?a. F (Fluorine)

b. P (Phosphorous)

c. Na (Sodium)

d. B (Boron)

HomeworkFinish Practice Questions

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