What is an element?
Transcript of What is an element?
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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)
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